Reply by Gene Howe

Once cured it’s inert. Safe for food. Hard to digest, though.:-)
I use System lll, and their syringes. Great for getting epoxy in small places like letters. Far less over spill mess and far less sanding, too.
Four routing letters…not carving…I lay down a piece of clear packing tape and rout through it. Then, leave it in place till after the pour. Just an idea.
Do keep us informed of you progress and experiences with the project.

-- Gene 'The true soldier fights not because he hates what is in front of him, but because he loves what is behind him.' G. K. Chesterton