Hollow Dice

I wanted to print a large dice for learning numbers for my grandson. It should be hollow.
I found a lot of dices here on thingiverse, but none of the found could be printed in dimensions like 55x55x55mm, with thin walls, and without beeing a hassle to remove the needed support.So I designed my own dice and tried to optimize the print. I know, it would be possible to use two different materials with dual extruder 3D printer, where the support will be water soluble, but I don't want to buy such a printer only for this print ;-)