Determining the perfect size
Not too big - Otherwise Rollgut will loose it's mobility.
Also not too small - Otherwise one couldn't carry enough favours.
After ended up with:
150 x XX x XX mm
Magnets to hold odds in place
It's magnetic, but you don't see the magic, as the magnets are assemblied from a hidden side.
All together four strong Magnets hold your magnetic writing instruments and small odds in position.