I needed a paid stamp so I thought I'd try and print one. PLA is not necessarily the best material but will be interesting to know if anyone can print (say) ninja flex.
I used librecad to create the letters.
opencad for the stl file
and slicer to create the gcode.
I cleaned it up with a Dremmel and used double sided tape to fix the stamp to a wooden block.
PLA does at least sand and can be remelted easily. I've found flatting off the surface with wet and dry on a flat surface helps debur the lettering. I also you a hot scalpel to remove any start stop nibs.