My friend wanted a white leaf for her betta fish to chill out on, so I tweaked hendo420's design to have a fatter "stem" and punched a hole in it for a suction cup hook. There are two files: one has a 2mm hole for the hook, and one has a 4mm hole for the hook.

I snapped the end off the 2mm hole print (pictured) while trying to bend the metal hook with pliers, so use some caution. This is just meant to be a thin piece that floats and is held in place just under the surface of the water, which is what bettas like, so it isn't particularly sturdy.