I love it when my hobbies interact to facilitate each other. I have some parts ready for paint - may get the paint going this afternoon - but once they are painted, I have to drill some holes on donor parts to mount them.
The directions for doing so are kind of rubbish. For example, they say to measure 2" from the center of an existing hole - and the picture shows a builder holding a measuring tape approximately in the center of the hole. Preferring some degree of precision and repeatability, I designed and am now 3D printing a marking gauge (the one in purple) that will let me mark that 2" more easily. The other two gauges will allow other, related markings. I'll post pictures of them in use once I get them printed and, you know, in use.