Some time ago I have been playing around with the Solid Works 3D CAD design software. The idea was to fully model a Heckler & Koch USP Expert 9mm gun by taking accurate measurements from the real deal and to use this CAD model in an animation movie. The two screen dumps below show the design of the slide is almost completed.

Only the internal part with the firing pin is still missing and some sharp edges would look more realistic with a small radius bevel.  A tray with 9mm ammunition was made as a first practice during evaluation of the software package, before I started working on the slide of the gun.  Since then, I have abandoned crappy commercial operating systems and with that I am no longer using Solid Works. When free time allows, I will try to export the CAD files to programs like Bender and continue this project.