I took the hammer holder and imported it into Tinkercad. The import didn't work very nicely, so I had to “cut off” the honeycomb at the back.

I then widened the space for the handle by thinning the hook arms.

I then imported a cup I had done a honeycomb for and cannibalised the honeycomb so I could attach it to the back.

Not at all my original design, but now my copper hammer can fit on this nicely designed hook.