If you are planning to carve a master and then make a mold and pour them with resin, there is a thread here about Art Resin that seems to be very good. I have not used it myself, so I'm just going by what has been posted here.
If you're going to carve them using wood for the finished bait, look for a decoupage type epoxy, like EnviroTex Lite. There are others, but I've used that one and it works.
It is designed to go over large wooden surfaces, like bar tops and tables, so it move with the wood as it expands and contracts.
I used to use two coats. I would put my bait on the turner in the evening, brush on the first coat, turn on the turner and check the bait for the first 30 minutes, so I could catch any drips or sags from too much material, or see any bare spots, in time to fix them before the epoxy got unworkable.
I would let the bait turn overnight, and then brush on a second coat and let it turn all day.
Because it is meant to move with the wood, it is stays flexible. Hard enough for bass baits, but not hard. A toothy critter can puncture it, and rocks will dent it. But it is the only top coat I found that would work with decent success on big wooden lures.
Good luck.