I had an old Pentax lens sitting around collecting dust, so I decided to try and mount it to my Nikon camera. I designed this lens mount adapter to use Pentax PK mount lenses on a Nikon camera body that uses the F-Mount. The focal length is very short, almost a macro.
Be sure to either use a dark filament or paint it black as there will be light leaks otherwise. I only printed it in white to show detail better. The last three photos are taken with the lens mounted on the adapter.
I was able to manually place my supports in Simplify3D. I put them under the main overhang but away from the mounting channels.