MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
The plastic on Amiga cases was ABS (I think) and the old/yellowed color is due to UV exposure, so you could try printing white ABS and then aging it under a UV lamp. Alternatively, you can bring an amiga back to new appearance with... acetone, I think it was. See Youtube.