Jeff:
The ACGG publishes a guide to having a custom gun built that is available through their website.
http://www.acgg.org/Click on the "Publications" or "Custom Gunmaking Resources"
As for the Guild show itself, wander around and look at the displays. Find a gunmaker or three that present a style you like and ask questions. That is what we all all there for. Just looking at all the work on display will fill you with new ideas and a whole list of things you didn't know you couldn't live without. Look around, ask questions, take notes. Most anything you can think of in the custom gun field will be represented there. Take pictures as well. Most everyone there will gladly allow photographs if asked.
See you there...Stop by and say hey.
Glenn Fewless
Member ACGG