Summary

This is a reproduction of the Vettweiss-Froitzheim dice tower (https://en.wikipedia.org/wiki/Vettweiss-Froitzheim_Dice_Tower), found not far from Cologne. The original was likely made as a commemorative gift in the 4th century AD.

I put it together by just gluing around the edges. Another, possibly better, approach might be to assemble the whole thing in software and print as a single piece, if you've got a big enough printer.