MPD

To create a Multi Part Dat file the following approaches may be useful.

Manually

Per the LDraw.org MPD Language Extension, the beginning of each submodel in an MPD file (including the main model) is indicated by a meta command like this:

0 FILE model.ldr

where "model.ldr" is the name of the submodel. Submodels may optionally be concluded with the following meta command:

0 NOFILE

The first model in an MPD file is considered the main model.

MLCad

MLCad can be downloaded from lm-software.com.

If you already have the files and just wish to combine them you can join them together in MLCAD

If you wish to create an MPD as you edit you may

1. Open MLCad.
2. Go to the Multipart menu and select New File.
3. Enter the name and details of the file.
4. Begin editing.
5. When you need a new submodel repeat steps 2-4.
6. When you wish to include a submodel in your current model go to the Document section in the Part selection list to select the model.

Bricksmith

Creating MPD files is a natural part of building with Bricksmith. Select Add Model from the Model menu to create a new submodel, or select an existing submodel from the Insert Reference submenu to insert an instance of that submodel in the current model. All submodels are listed in the Model menu as well as in the File Contents drawer, where you can examine their contents hierarchically or rearrange them via drag-and-drop.