What it does
LeoCAD is a free, open-source editor for virtual brick models. It uses the LDraw parts library, reads and writes LDR and MPD files, and supports submodels and multistep building instructions on Windows, Mac and Linux.
The basic tutorial builds a small racecar while showing how construction steps work. Choose a part and colour from the Parts and Colors panes, then drag the piece into Model View. Arrow handles move selected pieces, and the Rotate tool changes their orientation.
Click Next to advance the instruction step. In Timeline, drag a piece from Step 1 to Step 2 to make it appear only from the second step onward. Search Parts finds components by name, and Piece > Minifig Wizard adds a customised figure.
Movement Snap can prevent a wheel from reaching the precise position required by its holder. Turn off Move Snap Enabled for that adjustment, then restore a useful increment for repeated placement. Pasted pieces begin at the same coordinates as the originals and must be moved apart. Save the model when the sequence is ready; LeoCAD can print instructions or create a web page containing them.
The application uses GPL version 2. Its included LDraw parts use a separate library agreement, so software redistribution and part-library redistribution have different terms. LeoCAD is independent of the LEGO Group.
Strengths
- Submodels organise larger constructions into separate sections.
- LDR and MPD files connect other LDraw-compatible tools.
Best for
- Brick builders planning models and assembly order
- Creators preparing multistep building instructions
Sources
- LeoCAD | Virtual Brick Modelling (Oct 28, 2026)
- LeoCAD | Licence (Oct 28, 2026)
- LeoCAD | Basic Tutorial (Oct 28, 2026)