I design this simple duplication tool. Where you can put a pen or pencil on eachh side to create 2 of the same figure.

It have holes in each circle to hold the pen and also hholes thhrough the middle part to adjust the lenght.

Print in pla+ white with support ( I add a hole going throught one of the parts so its easy to remove the support, just insert the square into the other and push to get rid of support)