Bill,
Here's the short version:
I've made my own gear for quite awhile and have several molds. It's not that tough. the basics are to build the gear out of wood (I use scrap balsa). Get it like you want it, then glass it. I use 3/4oz glass and epoxy. Sand it, get it smooth and polish it out. Then build a box that will contain it. Cut drain holes in the ends of the box. I usually put them at the end of the gear. Split the box down the lateral center. Pack the gear in with clay in one side and get the clay smoothed out (I use a dental tool). half the gear (top or bottom) should be exposed. Wax up the surface of the clay and gear or shoot PVC molding release on it. I usually clamp the box back together, sealing the split line with duct tape or silicon. The pour molding material into the holes you cut. Sometimes it's easier to put holes in the area where the mounting plate for the gear is.
Once it's cured, split the box back apart, pull the gear from the clay and put it in the molded half. Seal it up with wax and/or PVC release. Dig all the clay out and clamp the box back together. Pour molding material into the other side. When it's cure, Viola!, gear mold.
It's really not all that complicated. I know this is a really brief description without much detail. I'd post some pictures buy my home computer is down right now (awaiting parts) so I don't have access to the pictures.
Once the mold is done, shoot it with PVC mold release agent. I use carbon fiber cloth and cut it into a lot of strips. You'll have to experiment in how much to use. It depends on the depth of the mold and how rigid you want it to be. I also use carbon tow for this. Usually a layer of cloth and several strips of tow and more cloth and more tow, etc. I use West Systems epoxy. Once the gear is done and popped out of the mold, I use a post cure oven. It's just a styrofoam cooler with a light bulb and a thermostat. Heat to about 175F for 24 hours, let it cool for a day and another 24 hours at 175F and you're done.
If you want to try this, let me know. I'd be glad to get a more complete description and we can jaw on the phone about it.
Try it, it's fun.