Wrap tape around the pot any way you choose. I did stripes here, and...
A solid block here. For the solid block, I wanted to cover a large section so I stuck scrap paper underneath the tape. Any section not covered by tape or paper will be spray painted.
Spray paint with chalkboard paint in a well ventilated area and let dry.
Peel off tape, identify your plant with chalk and plop your plant inside!