4.7.0 · Windows 10 / 11 · 64-bit · free
A lightweight 3D modeler for everyone on Windows: drop in shapes, type exact sizes
in any unit, cut and combine them, and export a watertight .stl ready to print.
No learning curve. No cloud. No account. No installer. Just one file that opens in a
second.
The Library — more than forty parts made to your numbers, from a box with a lid to a roof for a model house and the wheels behind a clock’s hands, each mechanism a working model to print and turn by hand. And Cladding and 3D textures to dress them: brick, rubble and coursed stone, siding, log walls, bark and wood grain.
Nine primitives on a 10 mm grid, or a custom one with its segments and roundness chosen before it is made. Type the size you want — not drag it and hope. Subtract, Intersect and Merge run on Manifold, a geometry engine that does not tear, and every result is checked: if one would not be watertight it is refused, and your object is handed back untouched.
Point it at a model and it decides which way the mold comes apart — a ring gets pulled along its hole, not across it — cuts at the widest section, keys the halves together, and drills the pour hole at the high point, with vents where a flat pocket would trap air.
Fourteen patterns — knurling, honeycomb, brick, roof tiles, planks, siding, rubble and coursed stone walls, bark, wood grain — each shown flat and in 3D before you apply it. Cut in or standing proud, on any flat face (even one that already has windows in it), around a barrel with no seam, or around the walls of a house. See the 3D textures. For brick, stone, siding and log walls with real corners, use Cladding.
Any installed font, or the filled shapes of an SVG. Cut, raised, beveled, and wrapped around a barrel or a ball — or bring the drawing in as a solid of its own.
Weld, cap holes, turn inside-out shells the right way. When that is not enough, Rebuild remakes the surface from scratch and Hollow turns a solid into a shell — with one side left open, if it needs one.
A tape that snaps to corners and edges, either end draggable. Fit check answers the question a render cannot: do these two parts actually meet, and by how much?
Cut a part too big for the plate and pin the halves, or pin two parts that already rest on each other. Pins go only where there is solid around them, spread out toward the edges, and pegs stand up out of the lower part — nothing hangs off an underside, and every one is marked on the cut before it is made. Or join them with brick studs, which hold by grip.
Turn a shape more the higher it goes, narrow it to a spire, or curve it over like a horn. Edges are broken up only where the curve needs them, so a twisted column stays light — and nothing is cut, so nothing can tear.
Studs on any flat face and the brick underside that goes over them, on the 8 mm grid — on a brick, a disc or a scan cut flat. A printable Fit test finds the tolerance your filament needs.
Extrude down cuts at a height you drag and carries the outline straight to the plate: a clean plinth under a scanned bust with a ragged neck, a body under a relief that is only a skin.
The project is a 3MF — 3D Builder's own format — that a slicer opens as it stands, with parts, names, colors and units kept. STL and OBJ in and out; SVG drawings come in as solids. Drop a file on the window and it comes straight in — a dropped project asks first whether to open it or join it to the plate.
Watertightness is checked on every export, and every risky operation says plainly what it did — or refused to do, and why. A modeling tool for printable parts should be hard to leave broken quietly. That is the whole design brief.
Each of these tools has a page of its own: how to use it, every setting in plain words, and pictures of what it makes.
Brick, stone, siding and log walls built the way the real thing is: whole corner bricks, cornerstones, posts over the boards.
Read the guide →Fourteen patterns for any face - knurling, brick, roof tiles, rubble wall, bark, wood grain - shown flat and in 3D.
Read the guide →Fixed, single hung, sliding and casement windows with muntins, an architrave and false shutters, ready to print.
Read the guide →Single, double, French and Dutch doors, square or arched, with sidelights, a fanlight and clear glass.
Read the guide →A silicone mold that comes apart: split at the widest section, keyed, with a pour hole and air vents.
Read the guide →Turn a solid into a web of struts: an openwork lamp or vase, or a light lattice that is still stiff.
Read the guide →Cut a part too big for the plate in two, and join halves with pins, pegs or brick studs that fit one way only.
Read the guide →Stand a part against a face, or put it on the middle of a hole: a pin in a bore, a window frame in its opening.
Read the guide →Fill what a cup, a box or a recess would hold if you poured liquid in, to a level, as a solid or a part of its own.
Read the guide →Choose the point a part turns and is measured about: a gear on its shaft, a lid on its hinge.
Read the guide →A 1:87 house built entirely inside the app, by driving its own buttons — then checked by ray-testing the exported STLs against a list of points. 74 checks, all passing.
The ribbon is split by what a tool changes: Edit changes the thing itself, Align changes where it sits, and Tools is the work around it — measuring it, mending it, casting it, and building it into parts that fit together. Nothing is buried in a menu. And if all of it is more than you came for, Classic mode puts the ribbon back to the tools 3D Builder had, and the Custom tab gathers whichever buttons you use most in one place. Whichever mode you pick, every key still works and no tool’s own settings are hidden — only its button.
§ 03.1
Nine primitives, a Custom shape with its size, segments and roundness chosen first, and the way in for anything made elsewhere. Every shape lands on the plate at a sensible size and takes the next color in a cycle, so a scene stays legible without anyone painting anything. Text makes lettering as an object of its own, in any installed font — flat, or bent around a circle or a cylinder. Sketch draws your own outline on the plate — lines, arcs, curves, freehand, rectangles, circles, or an SVG loaded in — and extrudes or revolves it into a solid. While you draw, the pointer’s X and Y are read off the axes and every line carries its length; a right-click finishes it. Import reads STL, OBJ and 3MF, and SVG drawings as solids; another 3DFastCraft project joins the plate rather than replacing it.
The Library (Advanced mode) holds the parts made to your numbers — boxes, hinges, fasteners, gears, windows, roofs, lithophanes, and the Fit test plates that find the tolerance brick studs need. See below.
On the plate: one of nearly everything on the tab — the nine primitives, a gear and its partner, a ratchet and pawl, an M8 bolt and nut from Thread, brick-stud fit plates, and the app's own name from Text — with the hexagon selected and its move arrows on it.
§ 03.2
Everything that changes the selection, down to its color. Undo and redo, Copy, Cut and a Paste that lands exactly where the thing came from — even in another window of the app — duplicate beside or in place, and delete.
Set pivot puts the point a part is measured and turned about wherever you click, instead of the middle of its bounding box — a gear turns on its shaft, not on the outline of its teeth; Pivot to center puts it back. Then Round, Twist, Taper and Bend to reshape it, Simplify and Smooth for a dense import, Hollow to save material, and Fill up, which fills what the part would hold if liquid were poured in from above, to a level — as a solid, or as a part of its own that fits the inside exactly.
Grow and Shrink move every face by the same distance rather than scaling — walls get thicker or thinner, gaps narrower or wider, corners stay sharp, and the height can be kept. Trim cuts a part back round its outer edge only, so an insert fits inside other walls while its partitions keep their thickness.
With several parts selected, the Move, Rotate and Scale handles treat them as one object; the Each button gives every part its own center and axes instead.
On the plate: a plain cylinder twisted into a vase, 50 × 50 × 80 mm and watertight, with the resize handles on it and the whole tab behind — undo through to color in one row.
§ 03.3
Where a thing sits, without changing the thing. Drop to plate, or Drop down until it rests on whatever is under it. Place on face lays a part on a face you pick — every face it can rest on is marked — and Best face down picks the face for you. Mirror it, and line a selection up on any axis — flush either side, centered, or spread evenly.
Align to centers one object on another. Align to face stands the selection against a face you click, or the middle of a hole, round or square, on whichever axes you choose. Center face to face puts the middle of one face on the middle of another, and reads both sizes and the gap. Fit shrinks a part that is too big for the bed, and Distribute sets a selection out in rows across it — and can turn each part onto its best face and drop it to the plate, ready to print.
On the plate: four M8 bolts spread evenly along Y, the whole selection moved as one — the status line says what it did.
§ 03.4
Cutting and joining first. Boolean arithmetic on Manifold with the app’s own BSP engine behind it — Subtract, Intersect and Merge. Any of it can be stopped part-way and leaves the model as it was; if a result would not be watertight it is refused and the objects are handed back untouched. Split takes a plane you can slide, tilt by dragging a ring, or set to a face you click. While you aim it the half that would be thrown away is faded, so you see what you are keeping before you commit — and the cut goes through the triangles rather than through the boolean, so a 200,000-triangle scan splits in a twenty-fifth of a second with both halves closed.
Measure, Fit check and Surface answer a question — how long, how far two parts overlap, and a face’s middle, direction, size and area. Measure snaps to the corner nearest you, chains several points with a total and reads the slope of a stretch; Surface can lay a face again from its outline, or clone it as a thin solid for a frame or a gasket. Repair mends a model that will not print, and Rebuild either keeps the shape and drops the points that add nothing — the web of thin triangles a subtract leaves — or remakes the surface from scratch when nothing else can. Mold makes a block to cast silicone in, cut so the casting comes out, with registration keys, a pour hole and air vents.
Voronoi cuts a solid into a web of struts — a shell that follows the surface for a lamp or a vase, or a lattice through the whole volume to take weight out of a part that still has to be stiff. Convex hull wraps a selection in one skin, Extrude down puts a flat base under a scan, and Repeat copies a part along a line, around a circle or in a grid. Studs puts brick studs, or the underside that grips them, on any flat face.
Emboss puts lettering, a drawing or a picture on a face you pick, raised or cut. Texture covers a face with one of fourteen patterns — knurling, honeycomb, brick, roof tiles, siding, rubble and coursed stone, bark, wood grain — flat, around a barrel with no seam, or around the walls of a house, and shows each pattern flat and in 3D before you apply it. Cladding builds brick, rubble, coursed stone, siding or log walls around a house the way a builder does, with whole corner bricks, cornerstones, corner posts and crossing logs.
Hole cuts plain, countersunk or counterbored screw holes, nut pockets and heat-set insert pockets. Keyhole cuts slots to hang a part on a wall, with printed studs and a drilling template. Split with connectors cuts a part too big for the plate into halves that pin back together — separate pins, pegs or brick studs, square to the cut, vertical or horizontal — and Connect objects does the same for two parts that already rest on each other. If there is no room for a pin, it says how thick the wall would have to be rather than cutting one through the side.
On the plate: a scanned head between the two halves of the silicone mold made for it, and Measure along an edge of one half, snapped to its corners: 135.09 mm.
§ 03.5
New, open, recent, save, and named versions kept inside the project file so you can go back to one — each with a small picture of the plate, so you can tell them apart by looking (Save version, Ctrl+Alt+S; Versions lists them). Export asks what to write before it writes it: everything or the selection, binary STL, ASCII STL or OBJ, and whether to drop the result to the plate; the project itself is the 3MF. Blueprint draws the model as an engineering drawing — front, top and right views and an isometric, hidden lines dashed, the overall dimensions and a title block — to print, or to save as a PDF.
The app opens on a start page — a new project, a file, your favorite projects and the last few, each with its picture. Project keeps notes in the file. Printer profile keeps a profile for each printer and filament: nozzle, layer, and the fits the tools start from. Shortcuts lists every key. Export session and Record (Advanced mode) write every undo step to a file, or a screenshot after every action.
On the screen: Export asking what to write — everything on the plate or just the selection, and which format — with the totals it is about to produce: 11 objects, 29,334 triangles, 326.6 cm³.
§ 03.6
Six axis views and isometric, Zoom to fit, an orthographic view with every edge drawn so a plan reads, wireframe, x-ray to see a part buried inside another, an outline, Overhangs to show in red what will need support, a grid, and the build plate at your printer’s width, depth and height. Units are millimeters, centimeters, meters, inches or feet, and every box and tool panel reads in them. Scale 1: changes no geometry at all — it tells you what a millimeter means, so a model reads in meters as well.
On the plate: the 1:87 house with its parts lifted apart, the units switched to feet and the scale list open — sixteen standard scales from full size down to 1:220, with 1:87 picked, so the floor slab reads 0.509 × 0.361 ft.
§ 03.7
The buttons you use most, in one place. Right-click any button on any tab — even a grayed-out one — and choose Add to Custom tab, or tick buttons from the Add list on the tab itself. What appears there is a copy that looks and works exactly like the original; right-click one to move it along or take it off. Your choice is remembered, in Classic and Advanced mode alike.
Windows 3D Builder was a beautiful thing: fast modeling for professionals and for people who had never modeled anything, with almost nothing to learn before the first part was on the plate. Microsoft retired it. This app exists to take its place: a free Microsoft 3D Builder alternative that works the same way — the same short path from a shape on the plate to a printable part. These are the thirty-two tools it adds on top.
Parts made to your numbers. Pick one from the catalog on the Insert tab (Ctrl+L), set its sizes with the preview standing on the plate, and insert it. The part remembers how it was made — select it later and Edit settings makes it again where it stands. Walls and fits start from your printer’s nozzle, layer and clearance, and every setting either makes a sound, watertight part or says plainly, in red, why it cannot. More than forty generators in nine groups.
The Library, the tools that work on a face, and what the File tab keeps. Click any of them to see it large, with what it shows.
One self-contained file. No installer, no .NET runtime, no account. Download it, double-click it.
Windows SmartScreen will object the first time — the executable is not code-signed. More info → Run anyway.
SHA-256c88c3997ceafa961a2893ecbf9e1fcc6393064a8502732aec75f64d6b495ed29
Also new in 4.5.3: Mirror reflects a selection as one, so parts change sides. In 4.5.2: a type for the Window with muntins, an architrave and shutters, Align to face on the middle of a hole, and a guide page for each of ten tools. In 4.5.1: every pattern shown flat and in 3D, siding and stone with no groove, a small picture with each saved version. In 4.5.0: a Custom tab for the buttons you use most, Extended mode folded into Advanced, the pointer’s X and Y read off the axes while you sketch. In 4.4: textures with no seam, assemblies, arched doors, dormers as parts of their own. In 4.3: projects are 3MF files, Esc in number boxes. In 4.2: printer profiles and their test print, Fill up, Library parts resized on the plate, number boxes that take +=5. In 4.1: the Library with working models, lithophane lamps and the moon, keyholes, pictures embossed, and the app in American English.
01 / 26
3DFastCraft 4.2 with a model house on the build plate: a hip roof tiled by the Library with a dormer merged into its slope, brick walls embossed around the door and the windows, a basement with its stair and balustrades, the windows and the door from the Library - each its own part, in its own color, and every one watertight.
02 / 26
Every mechanism in the Library made as a working model to print and turn by hand: a gear train and clock motion works on their bases, a Geneva drive stepping a slotted wheel, a four-bar linkage, a crank and slider, a pair of gears in mesh and loose spur gears. Each gear is keyed on a D-shaft that turns around in its bearing and flat where it drives, with a crank or a handwheel to turn it. Turn it plays the motion on the plate before anything is inserted and stops, in red, at the first jam. The Library panel on the right keeps the parts used last at the top.
03 / 26
An M8 × 20 bolt, a star knob with a pocket for an M6 nut, a washer to ISO 7089, a spacer, a knuckle hinge with its pin printed separately, a snap-fit hook and its catch, a cable clip, a pegboard hook and a holder for eight cells. Threads are ISO metric, cut as a die cuts them, with a clearance so printed parts screw together; fits start from the nozzle, layer and clearance set for your printer.
04 / 26
Prints that tune the printer, each labeled in the print itself: the 20 mm calibration cube with X, Y and Z on its faces, a temperature and speed tower in numbered bands, a pair of retraction towers, a bridge ladder of growing spans, a clearance plate of pins printed in place in their holes, brick fit test plates at four fits, and bolt and nut pairs at a run of thread clearances. Whatever fits best goes back into the app as the number to use.
05 / 26
A model house roof with three dormers merged into its slopes and tiled like the roof, a spiral stair with its handrail, a straight flight with a balustrade, and windows and doors: arched, round, half-round and rectangular windows, a paneled door and double glazed doors. Sizes are typed as the model is drawn and read back at its scale - set 1:87 and a door says how tall it would be for a person to walk through.
06 / 26
A cylinder standing on a cube, and the pegs that will join them: Connect objects finds the level face the two share - 0.36 mm apart here - and plans connectors through it, shown in blue before anything is cut. Separate pins, pegs on one half or brick studs; round or square; how many, their diameter, depth, clearance per side and distance from the edge. Both parts are kept, each as itself, and they go together one way only.
07 / 26
A pyramid cut by a level plane 5.84 mm up, the lower half given brick studs and the upper half the underside that grips them, so the halves press together and hold. Drag the plane or type its offset; separate pins or pegs are the other choices. The fit comes from the Brick fit test in the Library, and the cut face can be closed over.
08 / 26
A PNG of a dog traced into outlines - the dark parts, with the threshold at 0.58 - and cut 0.8 mm into the face of a pyramid, 16 mm tall. The handles on the face move and turn it; the corner squares resize it along the surface. Planar or wrapped around a curve, raised instead of cut, repeated across the face, or kept as a part of its own to print in a second filament. SVG drawings and lettering in any installed font are embossed the same way.
09 / 26
Two keyhole slots side by side in the back of a box, 32 mm apart, for screws with 8 mm heads: the head goes in the round end and the part drops down the slot onto the screw. Drag the handles to place them, set them one above another instead, and add printed wall studs and a drilling template if wanted.
10 / 26
A pin to be set on the hub of a gear. Click a face on any object, then for X, Y and Z choose a place on the face - its near edge, middle or far edge - and the point of the selection that goes there. The red marker is the place on the face, and the selection moves as one; nothing is turned or resized.
11 / 26
The side of a pin, then the wall of a hole: a round face is taken whole, by its axis, so Apply puts the pin on the hole's axis - turning it parallel first if asked - and the panel reads both diameters and the gap between them. Here a 5 mm hole in a cam has been picked; the pin goes into it next.
12 / 26
A plain box turned into an openwork basket: 120 cells, struts 1 mm thick, built on a 0.333 mm voxel grid so the result is watertight, with 57% of the material kept. Also the resize strip at the bottom - in millimeters or percent, with a switch - and the corners of the selection box, which resize in proportion when dragged.
13 / 26
Point at a face and it lights up; click and it is read: which object, the middle of the face, which way it faces and its normal, its size and area, and where it runs from and to. Here a strut of the Voronoi basket. Click another face to read that one instead.
14 / 26
Save version keeps a snapshot inside the project file itself - no copies of the file lying about. The list shows each one with its time and how many objects it held; Restore brings one back as an ordinary undo step, so Ctrl+Z returns to what was there.
15 / 26
Front, top and side views and an isometric of the basket on an A4 sheet, first-angle projection, hidden lines dashed and the overall dimensions drawn, with a title block. Figures too small to read can be left out, the drawing fills the page, and a second sheet lists the parts. Print it, save it as a PNG, or print to PDF.
16 / 26
Three printed parts of the 1:87 house shown apart: basement, living floor and roof, with dowel pins between each pair so they go together one way only.
17 / 26
Brick courses laid around window openings that were already cut: the pattern stops at each opening rather than running through it.
18 / 26
The house seen from above with the roof lifted off: six rooms, a hall and the opening for the stair.
19 / 26
A close look at the roof tiles, 30 × 20 cm each at full size: staggered courses, with a heavier line under each one.
20 / 26
A pen pot in two filaments: an orange shell with its lettering cut clean through, a blue sleeve that shows through the letters, and a pierced blue base beside it.
21 / 26
On the plate: one of nearly everything on the tab — the nine primitives, a gear and its partner, a ratchet and pawl, an M8 bolt and nut from Thread, brick-stud fit plates, and the app's own name from Text — with the hexagon selected and its move arrows on it.
22 / 26
On the plate: a plain cylinder twisted into a vase, 50 × 50 × 80 mm and watertight, with the resize handles on it and the whole tab behind — undo through to color in one row.
23 / 26
On the plate: four M8 bolts spread evenly along Y, the whole selection moved as one — the status line says what it did.
24 / 26
On the plate: a scanned head between the two halves of the silicone mold made for it, and Measure along an edge of one half, snapped to its corners: 135.09 mm.