if your problem is they don't make a
gobo that looks like what you want. Submit your design to
Apollo and they just might make it.
They, in fact, WILL make it. It's about $60 for the first one and then a
bit less for each duplicate, IIRC.
Back in the dark ages, before you could just Photoshop your
gobo up and email it off to
Rosco/
Apollo/Gobos-R-Us, I did some acid bath etching. I was rarely happy with the results. The process was balky, and moreover it was messy enough that I never could justify going to the trouble of refining it, particularly with regard to the ratio of water to acid in the etching bath.
Now, the acid I was using wasn't a professional etching compound, it was just hardware store stuff. I won't bother naming the acid I used because I think you should choose not to bother attempting to do this process, but to satisfy any curiosity you might have, and to convince you that this is a boondoggle....
The basic procedure was to get old aluminium printers plate, sand any coating off of both sides, draw your design on the plate with pencil or fine
point sharpie or whatever, then coat the entire sheet with
clear acrylic spray paint. Next, you'd take an
exacto knife and cut your
pattern through the acrylic. Finally, you'd immerse the plate in a bath of acid and water and let it burn through the metal where you'd cut the acrylic layer.
The big problem was that if the acid was too strong (or the plate was too thick) the acid would etch sideways under the paint, not just straight through the metal. So the lines wouldn't be nice and sharp, they'd have pits and bumps and such. And, the paint had a tendency to peel up off the metal if you didn't prep everything just so, or maybe even if you did.
But the biggest problems, and these are substantial, have been mentioned above in this thread: 1) You're working with nasty toxic stuff, and 2) what do you do with the used acid? The fumes coming off the bath were definitely in the "DON'T INHALE ANY OF THIS EVER"
category, and when you're done with the stuff you can't just dump it down the drain. You don't want to
spill it on yourself, you don't want to
spill it on your kid brother, you don't want to
spill it on anything, which begs the question, "Where do I dump this out?".
What I'm trying to communicate is this: Back in the day, before commercial custom
gobo fabrication was a matter of 20 minutes in PhotoShop, one email and a small fee, as a young and intrepid LD I felt pretty darn proud of myself that I could burn a mediocre
gobo on the concrete slab outside my garage. It was slick and clever and I felt like a cowboy. Woo woo. But at the end of the day, the gobos I made sucked, even by the standards of that time; and the process of producing those lousy gobos that sucked was dirty, hazardous to my health and environmentally irresponsible.
Stick with cutting foil
cookie sheets with an exacto or move up to having gobos etched by a shop like
Apollo that's set up to handle the process safely and cleanly. The "etch it yourself" option is a really lousy in-between kludge option that you should kybosh.