Nice work. Question: do you have a sample book that shows all of the patterns you have for signs? Not just pictures of items you've made, by computer images of possible designs? Not sure how your software works, but if it allows you to print a graphic image of every possible design, you could put in lots of variations and even stuff you could but don't currently stock? This sales and sample book would allow people to see items they COULD order from you and maybe even produce items with personalized copy. You could start accumulating these images, then put them into a Word document, then print it to a pdf (I use Cute PDF for that), then you can put this catalogue up on a facebook business page.
Add an order form showing the item number, the words you would like on it, plus a way to reach them. If there are size options, list them. How many words will fit will be an issue, but you can use a long string of small boxes they write their message in to set a limit. This sounds like a lot of work, but you build it up gradually, starting with popular items. As you make new items, shoot pictures and sub them in to replace the drawings.
You could also look for items that fit the region you're exhibiting in, for example for an Italian area, some pizza designs. And for impulse items, some 4 to 6 inch Round Tuits.
The more I do, the less I accomplish.