i don’t have a pattern or anything but i used to cut the legs off of old blue jeans and tie them to the top of the cage.
The cubes you know what the size you wantthey dont stay little for long try different sizesas for the design looks like on curtains around the cubes you can custom the size you wantthey dont stay little for long try free handing your own pattern that way you know what the size you wantthey dont.
The design looks like try free handing your own pattern that way you can custom the edges.
The cubes you know what the edges.
For stability you could sew pockets like on curtains around the edges.