The following is my opinion only. Others may disagree.
If you are considering putting an epoxy or other plastic finish on a pen, don't. I recommend using a good quality stabilized wood where the plastic resins are IN the wood, rather than as a transparent coating that is put ON the wood.
Epoxies are a durable finish for a pen, but there are some problems with them.
They take a long time to cure, and the logistics for handling several pens at a time can be a problem.
Any finish that we can put on a pen is only temporary. All finishes will wear, and there is nothing that we can put on a piece of wood that will look worse than an epoxy finish that is starting to wear through. Once there is a break in the surface coating, moisture and finger oils will migrate under the coating, and it will start to separate from the wood. The only solution is to use a coating that is thick enough that it will not wear away in normal use.
There are pencrafters who are casting the wood and other materials (things like snake skin and metallic foils) in epoxies and other plastics. This provides the thickness necessary to prevent wearing through the surface film, but this is different from using the resins as a "finish".
All epoxies will become an amber color with age and exposure to the oils, moisture, and acids from our fingers. How fast and how dark is a function of the resin, the catalyst, and the thickness of the coating on the wood. Faster cure times will generally turn a darker amber color faster than the slow curing epoxies, and a thick coating will appear darker than a thinner one.
Epoxies are a transparent plastic coating over the wood. They will wear like a plastic, and they will become opaque with abrasion and wear. Small scratches that are almost invisible on a natural wood surface will be magnified in the epoxy surface.
For these reasons, I think that a highly polished stabilized wood is the better way to put wood and plastic together in a pen. Or, remove the wood altogether, and make the pen from a plastic.