I am going to add two more historic murals to the Steidinger Tire storage building on Main Street in Fairbury. I needed to make 2 more pressure-treated mural frames.
I buy Select grade deck boards from Lowes, which are 1" thick, then plane them down to 3/4" thickness for the frames. These Select grade boards have very few knots, which is what you want to make frames with. The frames are roughly 92" wide by 40" high.
I route a 1 inch wide groove 3/16" thick, for the printed mural to slip into. The mural is about 3/16" thick, a decal printed on an aluminum panel. The printer temporarily tapes the mural to my frame in back, then I lift the mural onto the wall and screw the wood frame to the building.