I create molecular animations and use ChimeraX to import PDB files and convert them to surfaces which I then export for use in Autodesk 3dsmax. 

I have a very limited understanding of this fantastic software however I am wondering if there is a quick way to solve my problem.  I have a PDB file I was sent containing a trimer. When I use a command such as: 

molmap #13,1 20 (I found this on a YouTube video BTW)

It creates a surface model of the entire PDB file. How do I create separate surface models for each of the trimers? So the PDB exports with three meshes as opposed to a single mesh.

Hope that makes sense.