[Jeffy]

You might ask yourself if the belly pan needs to provide rigidity, or if it just needs to house electronics. In the past years, we have always used a box al welded frame and 1/8" lexan. The frame is solid without the lexan.

If you decide you still want to go with a rigid "belly pan":
I can give a +1 on garolite. I've always heard that it is about 90% the strength of carbon fiber. Machines just like carbon fiber or fiberglass in my experience.

As per your techno, if it is similar to the new one we got here, it can cut aluminium using a carbide endmil, and if you want some suggestions on speeds and feeds, I can give you first hand exerpience with a techno router. It's not fast, but it can be done if you decide that is what you want.

One other thing I remember hearing while lurking the forums was a suggestion to use a high quaility 5 ply 1/2" plywood. It's rigid and easy to work with.