Calcium water dish

[into]

I also make them out of white floral foam, covered with a layering of acrylic media concrete (sometimes called tapecrete)

Where can you buy that stuff? craft stores? One of the things I'm having fun with is trying to build new stuff instead of buying. I finished a homemade water fountain and a new modular 20gal terrarium (biuld out of two cheap $12 10 gal tanks) a couple days ago.