If I make an 8' x 12' billboard using 6mm (1/4") aluminum composite sheets, and have 2" x 6" crossers, do have to use plywood behind the ACM or can I screw it directly to the 2" x 6" boards?
Any tips? Do the screws want to pull through the sheets? Do you use silicone or Lexel to adhere the sheets to the crossers?
Any tips? Do the screws want to pull through the sheets? Do you use silicone or Lexel to adhere the sheets to the crossers?