I didn't have a great place to keep my food containers for my turtle & fish food, so I designed this holder to hang them from the side or front of the aquarium.

The uploaded files are 89mm and 67mm (please message me if you need another size, but don't know how to modify the *.f3d file!).  The holding features are designed for an aquarium with a 25mm ledge, and the “hook” is 8mm, to perfectly fit my 55gal aquarium.