Hi Vivian. I'm Cindy. Begin by purchasing round balloons at least 5 inches round. You will also need a bag of cement and colorant, if desired. Or paint color of your choice. Blow the balloon up. Place it on a cup that has been weighed down with rocks or sand, or anything you have on hand. Be sure to put the knot of the balloon facing down. Mix the cement according to the directions on the bag. Then start layering the cement on to the balloon. Try not to touch the cup with the cement. Keep applying the cement being sure to keep in the round shape. While the cement is still wet, make drainage holes with a Q Tip. (If you wet the Q Tip it will work better.) Allow to dry. Then bust the balloon. Paint it if desired. Vivian, this sounds like a fun project. I just might try this myself. Have fun.
Here's a cool idea: https://www.hometalk.com/38782838/diy-mini-cement-balloon-planters
Hi Vivian, we made concrete pumpkins using a balloon and you can find the easy to follow tutorial here https://acraftymix.com/blog/hollow-concrete-pumpkins/ They can also be used as planters