Looks like a fun project. There was a recent thread where JimmyD was asked about a fresnel light that he modified and added a flash head to. Here is the link he gave out:
About 6 or 7 months ago I bought five 9" fresnel lens with frames off of eBay. My plan is to use "concrete tubes" to build the sliding part of the lens. For those who want to see what these look like, here is a link of someone who was giving a bunch of them away.
Scroll down to see the photo of the concrete tubes. I found some at my local hardware superstore. They come in various widths and you need a set where one will just fit inside the other. This will be the sliding component needed for the light. The big ones are 9" in diameter and heavy enough to support the fresnel.
Here are some photos of the fresnel I bought (I bought 5, so would be willing to part with 3 of them which are still boxed).
Just to be clear. I have not built my planned light yet. I've just assembled the parts. I plan on using a novatron head for the first pass.