My sound holes are 3/8. For my pots with the holes on the back, I just use some 3/8 dowels, and an old 2x4 with drilled holes spaced out to hold the assembly. For my pots with the holes on the edge, I use a 4x4 that stands on edge, and have holes drilled in the sides. I spray them one by one, holding the pot by the dowel attached to it. I move to a different hole on the second coat. Pretty simple.