Actually green, but let's not spilt hairs.
Here are two of the three chalkboards I did for the brewery. I made the paint from 1qt of latex paint mixed with 2tbsp of unsanded grout and put it on two layers deep sanding back to get it fairly flat.
The frame is just half lap painted pine.
Mounted to the wall with two 1/4" plywood cleats behind them.
Nothing fancy, but it used up some of the stash of hardboard so I can almost get into the plywood pile now