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MLCad Screenshot

MLCAD (Mike's LEGO Computer Aided Design) is a powerful, yet easy to use virtual modeling program designed specifically for use with LEGO parts. Using the extensive LDraw LEGO parts library, it provides the ability to build almost any LEGO model virtually. No more running out of bricks half-way through the project--there's an infinite supply!

MLCAD is available for Windows and Linux (Mac users see Bricksmith or Mac Brick CAD), and includes support for English, German, Italian, Dutch, Japanese, Czech, French, and Spanish.


While MLCAD is fairly painless to install by itself, it is not a stand-alone program. The LDraw parts library is also required for operation. Though there are several steps involved in getting the parts library, it is not overly complicated. The official LDraw website has very clear directions for doing so.

Invalid LDraw Base Path Error
Windows Users
  • LDraw download and installation - Follow these instructions for installing the LDraw parts library
  • MLCAD download and installation - Download the zipped file containing the latest version of MLCAD from this page and unzip it into the LDraw root directory (any place will do, but this is the recommended location).
  • Navigate to the directory in which the MLCAD files were extracted and double click the "MLCAD.exe" icon. If an error message is displayed like the one in the image to the right, click the "Browse..." button and navigate to the LDraw directory (default is "C:\LDraw\"). The status should change to "OK!" and MLCAD can then be started.
Linux Users
  • Linux download and installation instructions - Follow these instructions for installing the LDraw parts library on a Linux machine
  • MLCAD download and installation - Follow the instructions on this page to install MLCAD on a Linux machine.


The best way to learn to use MLCAD is simply to play around with it. However, here are a few tips for getting started.

Browsing for Parts
  • Parts are grouped into seven main categories: Brick, Baseplate, Electric, Technic, Train, Plate, and Other Parts.
  • The tree menu on the left-hand side can be used to access all of the parts. Clicking one of the plus signs (+) expands a category to reveal all of the parts within it.
  • Clicking on a part's name reveals a small preview of it in the area below the menu, along with the next few parts listed after it.
Inserting Parts
  • To insert a part, simply drag and drop either its name from the parts tree menu or its preview image onto one of the four viewing areas. It is best to avoid dragging onto a 3D viewing area, as the location of the part cannot be specified this way (it is automatically placed at location (0,0,0), so it can come in handy at times). By default the lower-right viewing space is set to 3D view, but any of the other three will work just fine.
Viewing Angles
  • There are four view spaces in MLCAD. Each one can be set to a specific viewing angle. By default the top-left is set to "Front," the top-right "Left," the lower-left "Top," and the lower-right "3D." However, any of these can be changed to one of seven different angles (Top, Bottom, Left, Right, Front, Back, or 3D) by right-clicking anywhere in the viewing area and choosing "View Angle."
Placing and Rotating Parts
  • Once a part has been added, it can be moved around vertically and horizontally for precise placement.
  • Moving a part vertically is done by clicking and dragging it in one of the side (Left or Right) or Front/Back viewing areas. By default the top two viewing areas are set up for this.
  • To move a part horizontally, click and drag in either a Top or Bottom viewing area (use bottom left area with default settings).
  • Clicking and dragging in a 3D viewing area will not move the selected part, but instead change the angle of view of the entire model. This can be useful when wanting to see the entire model from a specific viewpoint, but still in 3D mode.
  • To rotate a specific part, use the arrows on the Transformationbar. This is hard to describe in text, so it is best just to experiment with this.
Selecting and Changing Part Colors
  • To select a part, simply click on it in one of the (non-3D) viewing areas. Alternatively the list of parts included in the model, found above the four viewing areas, can be used.
  • To change a part's color, select it and then click on one of the color swatches on the color toolbar.

For a more complete introduction to working with MLCAD, see Sebastian Stein's MLCAD Tutorial.

External links

  • Official MLCad website
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