[Freesurfer] Making a surface from the skull?

Hi all,

I know this is slightly outside the normal bounds, but I am wondering if there is a way to create a surface from the skull? One of our folks is looking to create some custom-fitted recording chambers for nonhuman primates based on the individual skull. I seem to recall that FS has a way of generating STL files, which would be perfect for submitting to a rapid prototyping machine. Here's what the user says:

" In brief, I would like to shape the bottom-side of my recording chambers (elliptical/circular cylinder) so that they form-fit to the curvature of the primate skull. Ideally, this will involve segmenting and extracting a 3D portion of the skull and converting it into an STL file to use for machining the implant."

Best,

mjp