A note about materials:
Paints: I have experimented with different types of acrylic paints for concrete and some failed. Not every type or brand mixes well. I found many that were very grainy and dry and ended up cracking where they were used.
The ones I know will work and am confident recommending are the Crafts Smart acrylic paints from Michael and also Amazon (any sheen is fine and indoor or outdoor will work). The other brands at Michaels didn’t work.
Sealers: I used sealer for this planter because I didn’t want the soil to leech through and discolor it. The brush on sealer does a better job of sealing, but will darken the planter. The spray sealer is what I used for the outside.