You can also choose whether for this molded, shape-reproducing patch to be laid up of a single layer of fabric, or else maybe two or three, if your repair is at a high-abrasion spot. ? Or as a sort of intermediate approach, if your underlying structural repair is kind of rounded at the edge, you can figure out how much gap there is at the corner, and fill just that part of the molded shape with some wetted-out strands of glass yarn laid in lengthwise, that you ravel from a scrap of glass fabric. ?

You can also fill any remaining space — or that whole space if you’re not so concerned — with a putty made of resin that you’ve thickened with a mix of microfibers and colloidal silica. ?The fibers make it sturdy (almost like a rock if you use enough) and the silica makes it sit still while you’re placing it — you can thicken it to where it’s like peanut butter if you need to — and the silica also gives a lot of abrasion resistance. ?(Something to consider before you use it in putty that you’ll need to be sanding.) ?Mix up an excess, and pile in some extra at the middle, tapering toward the edges, so that as you squash the patch into place it’ll chase out the bubbles. ?Then take your spreader and scoop off the excess squeeze-out, and butter the edges smooth (err on the full side so you can sand it flush).