I needed a hammer to help tap PINS into parts that needed to be split into multiple parts, so I designed the following hammer to suit my needs. One end has a square head, the other end is circular. the hammer also has a bit of weight/strength to use effectively.

Note: The STL provided is scaled to 100%, whereas the Print Profile is scaled to 80% - as it suits my hand a little better.

Also, Ignore the colors in the image, I printed this using the remaining filament on 2 spools, with a 3rd required as well (all spools were PETG).