A pinhole "body cap" for Nikon Z-mount. The printed parts are just the holder for the actual pinhole, you'll have to make one or buy one on Ebay (I got mine from fireseller66, a .15mm). Printed in black PLA, it's completely light tight even with sun shining on it directly.

Mirrorless is pretty ideal for this, since the short flange distance makes for a nice wide-angle view (as opposed to a DSLR where the pinhole is too far away from the sensor). For Nikon Z-mount, you end up with about 17mm of focal length and an equivalent f-stop of around 128 (if you use a 0.15mm hole). You can easily frame your image using the viewfinder, use the histogram and level, and even IBIS!

The printed parts hold together pretty well by themselves, but I glued them anyway to avoid them coming apart. To make use of the GCode posting here, I'm including two variations: the complete file below is both parts, printed in one color. In the user section, there are separate ring and disc files where the disc has a filament swap code to print the little alignment dot in a different color.

I designed this in OpenSCAD, the file is included. Sliced in Slic3r with the Archimedean spiral for the top and bottom layers (after separating the objects) to get a nicer finish.