I make a paste of water and plaster of paris, then mix it with chalk paint. Add more water if it's too thick, add more plsater of paris if it's too thin.
Here's a link with a great recipe:
Hi Ruthie, hope this helps you, looks pretty easy
Here is a recipe from Lowes: https://www.lowes.com/n/how-to/diy-chalk-finish-paint
I've used Kitchen & Bath semi-gloss paint and add 1/2c baking soda to take down the shine.
There are some great ideas here: https://www.hometalk.com/search/posts?filter=homemade%20chalk%20paint