In a medium bowl add the salt and boiling water. Whisk until most of the salt is dissolved, then whisk in the flour. (you won't be able to dissolve all the salt)

If there are any small lumps, use an immersion blender until completely smooth. (There will still be a little bit of graininess because of the salt but there shouldn't be any flour clumps.)

DIvide the mixture into small containers or little squeeze bottles, then stir in a drop or two of the food coloring to make desired colors. Store covered with a lid.

*The paint will seperate a bit when sitting for a while, just give it a stir before using.