Not an invention, but a technique.
This last weekend my clasp failed on my 30 year old tackle box. I figured, damn, I'm finally going to have to look at a getting a new box, but the wife said something about getting me a nice tackle setup for Christmas. Christmas! - I can't wait that long to go fishing again, and I can't go out with a broken box! Has to be a way to fix it.
Well I looked around my shop and came up with an idea. Reinforce the clasp top with a strip of brass and fiberglass cloth / epoxy.
First I scuffed up the clasp with some sandpaper and a wood rasp. Next I cut a strip of brass with my tinsnips and hammered the brass strip to fit the contours of the top of the clasp. I then glued the brass strip to the clasp top with 8 minute Lepages Epoxy steel. After that hardened I smoothed all the metal edges with my Dremel tool, and then re-scuffed the clasp again. Next I cut strip of fiberglass cloth to fit the clasp, and then coated the clasp with 30 minute epoxy, applying the cloth over the clasp and working the epoxy through the cloth with a thin wooden paddle. I then wrapped the clasp tightly with wax paper and set it aside to dry overnight. The next day I peeled the wax paper off the clasp, sanded anything rough, and sealed all edges with medium CA glue. When that dried I reattached the clasp to box and gave it a try. Works like a charm with the clasp tab not flexing at all. Job well done!