Welcome aboard, Jeff! You will find lots of helpful folks and information here on all things CBG (CBU, CBB, etc.) Feel free to poke around, ask questions, and post your stuff (photos, recordings, videos, etc.).
Most of all, have fun!
P.S.: in response to your question: some folks are using tarp grommets, others drain covers, but the "no rules" ethos / aesthetic is really strong here: you will find yourself looking at *everything* as a possible part for an instrument.