I printed this for measuring my bullets overall length for pointing with my hoover die. There's a 3d printed version available for purchase, there's also a retail version of this for sale but I'm too cheap. I printed this and ordered a thickness gauge from amazon.
https://www.amazon.com/gp/product/B07Q589VLQ/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1
I disassembled it and used only the gauge from it. I have the V channel designed to center up 7mm bullets, will probably work with others but that's what this one is designed for.
Mine is also printed in 2 different colors because I ran out of black while it was printing.
I printed this using PLA, the model was oriented to stand up vertically and with supports. I used 15% infill in my print.
The author marked this model as their own original creation.