This putty works for either tooling or marine applications. It bonds to fiberglass, SMC, BMC, RIM, and most other substrates. Every shop should have some.
A tube of appropriate size will be included with your putty. P-17 Black putty comes with black hardener, and the gray comes with red BPO, but if you want a different color (black or white), just write it in the notes section at checkout. If you want more than the required amount, get it here.