After seeing Wuvie's instructable:https://www.instructables.com/id/Easy-to-make-concrete-bowls-and-planters/
, I knew I had to do this. So, having all the available tools and materials on hand, I proceeded to make a functional planter using a plastic bowl and a bowling ball as molds. Having made several instructables that utilize concrete, I will refer you to those sites:https://www.instructables.com/id/Make-Unique-Planters-With-Concrete/
, for example and, of course Wuvie's excellent instructable, listed above.