Hi guys,
Thanks for your help so far. Every time I try and oversize the model and subtract the original in Autodesk Inventor I get this error.
" Create Combine feature failed.
nose2.ipt: Errors occurred during update
Combine1: Could not build this Combine
The attempted operation had problems trimming and discarding faces. Try with different inputs. "
Cubify Sculpt cant do it either and neither can netfabb basic. I have a limited amount of time to get this project finished and Openscad seems pretty complicated to learn from scratch. Plus my computer can't even seem to import a file using openscad.

What I'd really like to do is use something like the shell tool in Autodesk Inventor but the 3d model I'm importing has like 1700 surfaces so that's not possible. And if I derive the model as a surface and try and shell it, there is an error because the model has no volume.

Any other ideas would be appreciated.