No Supports required.
Planters are designed for and can hold as much weight as you'd expect to have in a standard 4" pot. Planter designed to be placed on 3/4" dowel, should be tight fit but allow movement into place. Takes two zip-ties per planter to secure itself, smaller size of standard thickness and width.
I also like to cut and hot-glue some non-slip material (like you might use in drawers or under carpet) to shape for the top and bottom models.
The author marked this model as their own original creation.