Rectangular Soap Holder - anti mould!

Soaps always tend to hold water under them. This causes sticky soaps, mould, etc. This is because the contact surface between the soap and its support is large, thus making it impossible for the water to evaporate. By minimizing the contact between the support and the soap, this support helps water evaporate faster, and also reduces stickiness.

The picture is actually a failed print (bad filament, dirty glass bed), it is still functional.