Attention Glassperts

[FishStretcher]

In a corner like that, upside-down?

Sandblast to prep. Then vinylester. In small batches. Wet the surface, apply dry mat. Wet with VE. Let it gel. Then repeat with a larger patch of mat. Do this for 4 or more layers? You need VE as it has the flexibility and will dissolve the binder in the mat plus you can tune the tack time. Polyester won't flex and epoxy won't dissolve the binder in the mat. You have to mix in an unwaxed cup. Sometimes solo cups will hold together long enough, but likely not. A dozen chip brushes and maybe a half gallon of VE and at least 8 polyethylene quart mixing cups should do it.