On 9 July, 13:33, manyirons wrote:

and I'm thinking epoxy would be the best choice.

Decent epoxy, filled with phenolic microballoons to the consistency of
peanut butter. For paler wood, silica microballoons with a dye. You
can apply this with a popsicle stick, you don't need a mould.
Microballoon filler is useful because it's easy to sand afterwards.