Hi Sc0rnd. I finally did photograph a bee's face for WPPD a couple years ago with that pyramid camera. Well, it was a yellow jacket but same idea
View attachment 401789
this is almost a "pinhole microscope" because it is much more than 1:1... the negative is on 5x7" photopaper and the face is maybe 1/8" wide. It's difficult to light the subject when it is close to the camera, and the pyramid shape helped a lot with that. This image took 6 or 7 hours with two bright reading lights on either side. Getting it centered in front of the pinhole was difficult. I tried a few times and one time the little hairs on top of the thorax were well defined in the image ( those are tiny! ). I'm certian this image could have been much better if I'd spent more time on it... the pinhole size was a bit too big. I was intent on making the face fill the photo paper.
In macro photography with a lens thin depth of field is a problem. A similar but less extreme thing happens with pinhole. For example, the magnification factor for a plane 1/4" from the pinhole is twice as much as the plane 1/2" from the pinhole. That makes a big difference in the "optimal" pinhole, enough that it matters to the percieved sharpness of the image.
Best thing to do is build a simple camera and give it a try! For more normal macro, like 1:1 or larger, it can do surprisingly well and the pinhole size is not so critical.
Have fun!