Warming up the geometry kernel…
drag to orbit · scroll to zoom
Z Y X
Change this shape to…
Colour this shape
Cheat sheetclick anything to insert it
Sizes are in millimetres. Angles are in degrees.
BREPcodebuilds as you type
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Starting…
Historyedits & features
Build a model first.
Assistantbuilt-in
only used if you ask for it
the full instruction set sent to the AI — same for Gemini and Claude
Key is stored only in this browser (localStorage) and sent only to the provider you pick.
RandoTechNerdBREPcode.com · v0.4.0
Documentation — every modelling capability below is the BREP.io CAD engine, built by @mmiscool. BREPcode is just a different way to “call” it — a code + direct-manipulation front-end over his kernel (source).
The desktop app talks to your own Claude Code — install Claude Code, sign in once, and pick Claude Code under Provider in the AI window. Chat then runs on the Claude subscription you already have: no API key to paste, nothing metered per message, and the model runs on your machine rather than through this app's servers. The dot beside the chat box lights up when it is connected. Everything else — the built-in provider, Gemini, GPT, a local llama.cpp, or a model in the browser — still works exactly as before.
Build a model — type BREPcode (OpenSCAD-flavoured JS) in the editor; it rebuilds as you type. Or paste OpenSCAD, JSCAD, build123d or CadQuery — it auto-detects and translates. Press K for the cheat sheet; click any entry to insert it.
Shapes — cube, cylinder, cone, sphere, torus, and 2D polygon + linearExtrude / revolve (lathe).
Combine & shape — union, difference (holes/cuts), intersection; fillet and chamfer to round or bevel edges.
Move — translate, rotate, scale, mirror.
Edit a real part — import an STL/OBJ/3MF, then drill holes (difference), add on (union), or split & fill the middle (stretch) to make it longer. Multi-body files import as separate solids. In the cheat sheet, the “Edit a part” items wrap whatever model is already in the editor.
Edit by hand — drag a shape to move it, drag its faces or corners to resize, right-click for per-shape colour. Click a word or number in the editor to highlight it on the model, and vice-versa.
Import — STL, OBJ and 3MF meshes (Import button, or point the Model folder at a directory to browse thumbnails). Meshes come in as solids you can cut/drill/stretch — note it’s mesh geometry, not editable CAD parameters.
Export — STL / OBJ / 3MF (print & DCC), STEP faceted and true curved B-rep, an SVG 2D drawing (projection with hidden lines), and for the web a GLB or a self-contained Embed page that shows the model with the free model-viewer component.
Assistant — a built-in shape bot handles simple asks; add your own Gemini/Claude key (⚙ in chat) for full natural-language modelling.
More — image → outline tracer, procedural textures & lighting, themes, edit history (◀ ▶), and keyboard shortcuts (the Keys button in the cheat sheet).

Links
WebsiteRandoTechNerd.com
YouTube@RandoTechNerd
DiscordJoin the server
Coffeebuymeacoffee.com/randotechnerd
EmailRandoTechNerd@gmail.com
Keyboard shortcuts
E editor · M material · H history · C chat · K cheat sheet · I info
← → spin view · tilt · Home reset view · Esc close
Credits & licences
Built on the open-source CAD kernel from BREP.io: all solid modelling here is its engine. Credit and thanks to its creator, @mmiscool (source).
This fork lives at github.com/RandoTechNerd/BREPcode. Inquiries: RandoTechNerd@gmail.com.
Gridfinity is an open standard by Zack Freedman, licensed CC BY-NC-SA 4.0. The bins and baseplates this tool generates follow that standard, so what you make with them is non-commercial, must credit the standard, and must be shared alike. Dimensions here follow the community Gridfinity Design Reference.
Theme
Model inventory
Parametersthe model's own dimensions
Millimetres. Changes are written straight into the code — undo still works.
Material preset
Surface
Texture
Shading
Per-shape colour
Medium
Colours are spread across the shade you pick, so a QR code or a row of parts comes out multi-coloured but all in the same family. With a shape selected only that one is recoloured — so one part can be dark and the next glow. Or right-click any shape to colour just that one.
Named spool colours inspired by Cookiecad filament.
Trace imageoutline → extrude
Threshold 128
Detail 1.3
Size (mm) 60
Height (mm) 4
Parts shelfalready written, already building
Click a part to drop its call into the editor. Everything is parametric — change the numbers after. CUT parts get subtracted.
Gridfinitydrag out a size
1 × 1
Drawer
Know the drawer instead? Put its inside measurements in and the grid sets itself.
Cookie cutterpick a shape
Icons from Iconify — check the licence of the set before selling prints.
A shared modelshared with you
It travelled inside the link — nothing was uploaded, and it is not stored anywhere. Drag to spin it.