With a little bit of 3-4 mm paracord and 5x1 mm magnets, this holds super nicely.
Filler, sanding, then a little bit of airbrush and… here I got it using 3 central pieces
The lowest part is for “small” dice of below 18.2 mm in height, all others allow up to 24.8 mm
The author marked this model as their own original creation.