Without seeing exactly what you have, it's hard to advise what to do.
I once had a claw foot sofa with deformed/damaged claws. I cut the damage off, leaving a flat surface, then glued flat-surfaced wood to the cut site, then carved new claws. I suspect this was easier than forming a mold, as you propose. Carving dried glue or epoxy would be difficult, not to mention successfully applying a stain and/or finish onto the glue/epoxy area. *Tinting the epoxy would be an option for stain, but that's extra work and/or too much trouble, IMO.
If carving new claws, practice on some scrap wood to learn how to carve/shape appropriately.
As to gluing new small pieces of wood onto a small cut site and/or mis-shaped area, use rubber bands as your clamp. A sample of rubber bands could be stretchable electrical tape, typical rubber bands or make rubber bands with tire inner tube material. I have several sizes of inner tube bands I use for clamping awkward pieces. They are made by cutting 1" strips of bicycle, car and tractor tire inner tubes. You can buy tubing, similar to chemistry lab Bunsen burner gas hose, but making simple flat strip rubber bands works just as well. If you elect to use rubber band clamps, do a dry fit clamping (no glue), first, to see how you will clamp things in proper place, before committing to the glued-up finished product. Clamping awkwardly shaped pieces most often takes a little practice to get things right, to get things aligned properly, etc., before committing to the glue-applied piece, assuring
the securing of things in their proper/good position.