Bill Houghton, Sebastopol, CA
You can get a liquid plastic that air-hardens, sold for protecting tool handles and the like. It comes in a can similar to a Pringles can, and you dip the tool in, pull it out, let it air dry, and repeat until you've got the thickness you want. I've thought about buying a can, wrapping plastic wrap around the end of a chisel/gouge/whatever, then dipping the end in.

But, again, I haven't tried it, and haven't read the safety instructions, so don't know if the plastic would eat the plastic wrap, and so on, or how effective a protector cap it would make. But you might look into it. If you do decide to try this, please report back.