Click a face, change a number: editing 3D models without re-prompting
Not every edit needs the AI. Click any part of the render, see its dimensions as editable numbers, type a new value and recompile locally in a second.
Three ways to change a model
| Method | Speed | Best for |
|---|---|---|
| Type a number in the viewer | About a second, no AI | Dimensions that already exist as parameters |
| Fast mode chat | Seconds | Small edits: sizes, holes, tolerances, counts |
| Smart mode chat | Longer | New features, redesigns, anything that needs reasoning |
Most people start with the chat for everything and discover the viewer edit later. Use both.
Editing in the viewer
Click any surface of the render. A panel opens next to the click showing the size of what you selected and the parameters that shape it: wall = 2, hole_d = 6.4, height = 40. Type a new value and the program recompiles in your browser, no AI involved, no waiting, no credit. The previous shape stays visible as a ghost until you keep or undo.
Click a face that belongs to a named part (the lid, the clip, the standoff) and the panel narrows to that part's parameters. If the program has no part names yet, one click asks the AI to add them.
When to use the chat instead
The viewer edits numbers that exist. It cannot add a feature that does not: a new hole, a chamfer, a slot. For those, the same panel has a text box scoped to the selected part: "add a 6 mm hole through here" is sent with the selection attached, so the AI knows exactly which face you mean.
Fast versus Smart
Two AI modes are available on every message:
- Fast uses a quicker model with light reasoning. It is right for "make it 2 mm wider", "add two more vents", "change to M3". Most iteration happens here.
- Smart is the strongest model and thinks through the geometry. Use it for the first version of a part, for anything with moving pieces or fits, and when Fast gets something wrong.
Switching is a toggle above the composer. Every new visit starts on Smart so nobody gets stuck on Fast for a hard problem.
The ghost
After any change, the model as it was is drawn as a translucent overlay on the new one. Walls that got thicker show as a double outline; a moved hole shows both positions. Keep or undo with one click. It is the fastest way to answer "what did that change?" without reading code.
The code is there too
Every model is readable OpenSCAD. Open the code view, and you will see the same parameters the viewer showed. Power users edit there; everyone else does not need to know it exists. Download the .scad file to keep a fully editable copy outside SpeakCAD.
Putting it together
Generate with Smart. Iterate small changes with Fast or directly in the viewer. Use the ghost to check. Print. Fix measured errors by typing the numbers. That loop is why people design ten versions of a part in the time a desktop CAD program takes to open.
Prompts to start from
Open one in the builder, change the numbers to yours, and the model renders in seconds. Keep adjusting in the chat before you print.A drawer organizer tray 200 x 120 x 40 mm with 1.6 mm walls and four compartments. Name the parts 'tray' and 'dividers' and make the compartment count a parameter.
A knob for a 6 mm D-shaft, 30 mm diameter, 15 mm tall, with 12 grip ridges. Make the diameter, height, ridge count and bore parameters.
Questions
Yes. Click a face in the viewer and type new values for the parameters shown. The program recompiles locally in about a second. The AI is only needed when you add or remove features.
Fast is a quicker model for small edits like sizes, holes and tolerances. Smart is the strongest model and reasons through geometry; use it for new parts and redesigns. You can switch on every message.
A viewer edit is a small parameter change, so re-downloads after it are free under the small-edit rule, as long as the volume and size did not change drastically.