The aluminum mast step was fastened to the base with lag bolts. Naturally, once the repairs were completed, this fitting would have to be bolted in exactly the same place. So, before covering the bolt holes with glass, I inserted into them pieces of threaded rod wrapped in masking tape and smeared with Vaseline. After the epoxy cured, once the rods were removed, the original fastener holes were accessible. Next, I mounted the aluminum fitting on that piece of prefab glass I intended to install and drilled the bolt holes with a drill press. The guiding pieces of the rod went back in, once again covered in Vaseline. Then I installed the prefab piece of glass onto the original base, covered with thickened epoxy resin. After removing the rod guides, I bolted down the aluminum mast step using the original holes.