An adapter to digitize old slides with a DSLR with a macro lens. In particular, designed for AF-S Micro Nikkor 40 mm 1:2.8G DX with an outside diameter of 68 mm.

Print the parts, assemble with glue or gaffer tape, fashion a light diffuser out of while office paper and attach to the adapter. Fine-tune the fit of the hood on the lens with gaffer tape, too. 

The design is pretty crude and can be improved a lot, but I used it once and don't have a need for it any more.