Plus, they can be wiped off and re-written with name, for a birthday, with a monogram, for Bunco night...whatever! For the last day of school we wrote "Thank you for helping me bloom!"
I purchased the vases for $2.50 in the Dollar Spot at Target. I already own chalkboard paint from Greta's Paris Spa Party.
I simply filled in the space between the grooves with two coats of chalkboard paint freehanded. You could also use a stencil to fill in a simple space, but your writing area would obviously be smaller. The chalkboard paint dries pretty quickly, so if you make a mistake you can use a damp paper towel to wipe it off.
Once your two coats have dried for 4 days (or the recommended for your paint brand) you can just cover the entire chalkboard surface with the side of a piece of chalk to "season" your chalkboard. Then wipe that off and you can write and erase to your hearts content!
We filled my MIL's with water for Mother's Day and realized it was not water-tight...so when we did the teacher gifts I just tucked paper towels around a plastic party cup and filled that with water.