Lyman's Case Prep Multi-Tool has a hollow handle, so you can store its various bits inside it. But they just rattle around in there. I designed this core to fit in there and hold the bits securely.
The holes on the ends for the deburring cutters are not threaded. But the holes are slightly undersized in the last few mms, so the cutters can make their own thread. Just turn them in gently the first few times.
I wanted it to be able to print without supports. I did a few little tricks to make that possible:
The author marked this model as their own original creation.