Shouldn't this post be in the wire bait section, the place were the real men post !!
I've done a bit of R&D (rippoff and duplicate) of a related lure, the Zzinger.
This mold was my first Bondo mold and was made in 1988. It's 20 years old and has poured over 50 castings. (Ignore the 2 holes that I drilled in the back of the casting, it was a balancing experiment)
Luckily I saved a private message about how I make my Bondo molds. I hate re-typing stuff
First you need a pattern, or master that you're going to copy. It can be
made from metal, wood, plastic, etc., but it must be fairly strong and
rigid, have a smooth surface, and have no undercuts, so that it and the lead
casting will come out of the mold. You could also copy an existing
lure as well.
Here