Hahaha That "great minds" thing is a stretch.
I was pleasantly surprised when my first plopper, three years ago, actually plopped more loudly, and outfished my factory made ones, so, of course, I set about building them like crazy.
I've learned enough now to be able to shape one in an hour, but fine tuning the plopping tail still involves test swimming, so it's far from an exact science.
I did learn that having the tail just slightly down is key for me, because the PVC I carve it from is so buoyant that it won't plop at low speeds if it sits level. The original hangs down at more than a 45 degree angle, so it's tail is already turning by the time it gets up to even with the water's surface.
A combination of a thinner "shaft" for the tail, with less buoyant material, plus additional belly weighting in the back part of the front section, allows me to adjust the angle of float at rest, and to get a good plop at low speeds.
The actual cupped fins on my PVC tails are thin, so they do not have enough tensile strength to take impacts with hard objects, but fish up to seven pounds have eaten them with no breakage or damage. I typically coat them with gap filling super glue to provide some reinforcement, but I don't throw them around rocks.