As far as filler I used what I had in the house, had some clear automotive lacquer that I mixed with some sawdust. I think your polyurethane or epoxy mixed with into a slurry would be what I want to use.

I was amazed at how easy the keys came apart. I first thought that they were molded but they snap together.

A fixture would be nice to slot the wood. I used a ceramic stone and then a drill bit to open it up at the ends.

If you have 1/8th inch wood you could cut the slot in one piece and save half of your material.

Down here in Missouri I have not seen any zebra wood growing but I do have my eye on some burls.

__________________
85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.