Get yourself some heavy-duty disposable
cookie sheets and and an eXacto knife and have yourself a time.
Before
Apollo and others made the cost of custom steel gobos affordable, many kits and instructions were available involving sheet stock, resist media, and acid-etching. Most provided only marginal results and the cost of materials rivaled purchasing stock steel patterns.
Consider borrowing or renting for a nominal free, gobos from a nearby H.S., College, Community, or Professional
Theatre. We could even start a "
Gobo Exchange" right here on CB.
"Got any Medium Breakups?"
"Go phish."