A Tinkercad alternative for parts with real dimensions

Where Tinkercad is still the right choice

Tinkercad is free, runs in any browser on a computer, and its dragging and grouping of blocks is the gentlest introduction to 3D there is. For a child, a classroom, a keychain, a nameplate or a quick arrangement of shapes, use it. It also exports more formats (STL, OBJ, GLTF, SVG) and connects to the rest of Autodesk's tools.

Where it runs out

Three things make people look for an alternative, and all three show up the first time a part has to fit something:

• No fillet tool. Rounded corners are built by hand from cylinders, and they have to be rebuilt when the part changes size.
• Numbers that are not linked. Each shape has its own size and position fields. Make the box 5 mm longer and the holes, the lid and the cutouts stay where they were.
• No phone. Tinkercad's own requirements say phones are unsupported and the window must be at least 864 px wide.

What SpeakCAD does instead

• Six tools, in millimetres. Hole, Cut, Add, Extrude, Round and Measure on the face you tap; every number typed, with M-size presets and a through option. A hole, a cut or an added shape lands where you tap, and its Position rows set its centre in millimetres from the face's edges (Centre 12 mm from the left edge), before you apply it or later on its card. Extrude pulls a whole flat face out, or pushes it in, by the distance you type; a curved face is an AI request. Round rounds the corners of a part: the edges parallel to the normal of the face you tapped (a pocket you cut by hand gets its own corner radius). Rounding a single edge, or the top edges of a box, is an AI request.
• Linked dimensions. Starters and AI designs are programs with named sizes: change the width later and everything built from it follows. A hand edit stays where you placed it and is a numbered version with undo; after a resize, Measure it and move it on its card if it should have moved.
• A phone editor. The whole editor runs in Safari or Chrome on a phone, with the tools in a bottom sheet.
• An AI when you want it. Describe the part or the change in plain words, including the things the tools do not do (a single rounded edge, a snap fit, a hollow). It is optional and it is what spends credits.
• Print-ready files. A watertight STL or 3MF, or G-code already sliced with your printer's official profile, and Fit Check to calibrate clearances to your printer.

Moving a Tinkercad model over

Export the STL from Tinkercad and upload it with the Upload an STL or 3MF card in a new model's empty editor, drop it on the Edit an STL box with the change left empty, or on the online slicer and press Change it with AI with nothing typed (SpeakCAD's card in ChatGPT or Claude works the same, with no change): it opens as a model with no AI turn. Hole, Cut, Add and Extrude (on a flat face) work on it by hand and Measure reads it. On your own STL or 3MF opened with no AI turn, the whole file is one part, so Round rounds the corners of its outline seen from the face you tapped: right for a boxy part, and refused when the radius would take off more than the corners. Shaped only by hand, it downloads free with a free account.

Type a change with the file instead, or attach it in the editor's chat with a sentence, and that is one AI request (2 credits): the AI opens it with its holes measured, so it changes what is there instead of guessing, and the model's download then spends 4 credits.

What it costs

Shaping a part by hand (a hole, a cut, an added tab, an extruded face, rounded corners) and downloading what you shaped are free. Each AI request spends 2 credits, a download of AI work 4 credits, and G-code 5 more. Free, no card: the hand tools and the files they make, the live demo (3 AI edits of a real part, no account) and the 650+ ready-made library models. Maker is $7.99 a month for 60 credits, cancel anytime; see pricing. The full comparison is on SpeakCAD vs Tinkercad.