I quite like the apparent simplicity of this design:

Folded from a square split on the 1/3 line, larger piece making the base, smaller for the lid, this ingenious design neatly makes a moneybox, coin slot and all.

Designed by Mathieu Tournadre, it is a nice little square box with a coin slot that is adjustable to accommodate different sized coins, and nicely takes advantage of duo paper.

I reversed the paper for the lid to give an interesting contrast – fun fold