This is a set of calipers I designed for measuring turtles. Most off the shelf calipers don't have long enough jaws for the task, and those that do tend to be very large and unwieldy. I designed these to be just large enough for the job.

The screws used are two M3  8mm long, plus one M3 nut.

I printed these with a colour change for the text layers on the main body, plus the first layer on the sliding jaw, so these two parts had to be printed separately.