Ignoring parts

You can use the following commands to ignore parts:

0 !LPUB PLI BEGIN IGN
0 // This won't show the part in PLI, but if it is a submodel, it will generate building instructions.
0 !LPUB PLI END

0 !LPUB PART BEGIN IGN
0 // This part will not show up in PLI and if it is a submodel, it will prevent creating building instructions.
0 !LPUB PART END

So, either of these will make things not show up in the PLI. The first one will also prevent building instructions for the things enclosed like submodels or so called sub-assemblies.

You can use the second one in combination with the substitude (SUB) command to get parts that actually are made from more parts as one part in the PLI.

The hinge brick for example:

Create a submodel hinge.ldr and make the hinge brick from its two parts.
Use this new submodel as part in your model and use the following code:

0 !LPUB PLI BEGIN SUB hinge.ldr 0
0 !LPUB PART BEGIN IGN
1 0 10 0 -30 0 0 -1 0 1 0 1 0 0 hinge.ldr
0 !LPUB PLI END
0 !LPUB PART END

Note to use the same color code in both commands. It is best to use black (0) for coloring submodels.