Because I have a solid backing I wanted to create an easy way to access my lights inside the sign so I created a channel around the front of my frame that I could easily slide my main panel in and out of. The metal is just 1 inch by 1/2 inch drywall corner molding. This works perfect as it gives me a 1/2 inch of coverage to keep my panel in place plus the bottom side has holes already in it to allow any water that gets inside the channel to drain out.
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