This is a self-watering (aka bottom irrigation) planter that I created as an easy 3D print.

It can easily be scaled to fit your space and plant, although 50% is probably the realistic minimum size. The full size version works well on a window sill.

This is three-piece print is designed to print well on any 3d printer without supports. If you have it, it is a good idea to use a second color for the float to make it more visible.

More information can be found on the Easy 3D Print page. The STL files are available on Thingiverse.