Oh, and I don't recall if this was mentioned, but with your skill, I would print some paperwork for custom work to the show. Put up a big sign (in metal!?) stating that you do custom work. Hand out the custom order form with whatever information you think relevant. Rough ideas would be base costs for panel material by type and size, premium for difficult material selection (steel?), maybe some guidelines for framing/shadow-box (look at sites that do that for ideas on how to estimate), whatever you come up with. They fill out your form, include a sketch, image, URL, something to provide you with the desired design, and you can figure things out at home, then email them a quote. Don't forget, everything you offer needs to provide some sort of margin for you, including materials. Get a professional account to get discounts when you buy, and mark it up to roughly (or a little more) market cost, and that's just materials. If you don't want to get into framing and such on your own, find a local shop that will do it and get a "wholesale rate", which again, you get a margin on. If you can't make something on it, refer them to another business to handle that part. There may be something said to just doing a pass through (no profit) on something (like framing?) just to build your market, or it may just be necessary to get your core product sold (and thus profit). But in general, every really successful business man I know had the general rule of thumb that anything they touched had to provide at least N% profit. If they couldn't get that, they farmed it out, perhaps even facilitating the connections, but what they did always had a profit margin (mark up).
Again, just a few thoughts from the peanut gallery. I see some significant skill there, and would like to see you succeed.