About this 3D model
I have 8x3mm magnets instead of 6x3mm magnets which the original thing was designed for so I just enlarged the magnet hole in tinkercad. I used a hole diameter of 8.2mm in the design, and my 8x3mm magnet press fits in perfectly and holds without any glue. The handle is unchanged from the original Thing (https://www.thingiverse.com/thing:2485766). I also uploaded the handle as a file for convenience so you have it all in one spot. If you prefer to have the magnet enclosed/sealed in the hammer check out this other one here: https://www.thingiverse.com/thing:3314362