See the PIL-box project at http://www.jeffcalc.hp41.eu/hpil/

It's a pretty easy print. Took 30 minutes at 0.2mm on my Ender 3.

The interesting part is how it was created. I scanned the included end caps on a black background, used Inkscape to extract the contour of the part and then proceeded to save it as an SVG. Used a black marker on the part to hide the thinner border, scanned it again and created another SVG. From there, I extruded the shapes in a CAD program and exported those STLs. It fit very well on the first try.