Auto body repair & detailing: Replacing floor pans, crash worthiness, lumber work

Question
I need to replace floor pans on a vintage euro car.  Replacement panels will run close to $1000+ shipping, so I'm looking at fabricating my own.  I've read that fiberglass can be used instead of metal, but have not found any info on fabricating new pans.  Is it safe to make panels out of flat steel or fiberglass?  What is the usual method of replacing floor pans when replacement pans aren't available (or too expensive).  

Thank you!

Answer
Absolutely do not try to fiberglass in the floor pans, the car is probably a unibody. The floor gives the vehicle some of it's strength, and rusted floors repaired with fiberglass mat will reduce it's crash worthiness. Fabricating panels basically means careful measuring, and  purchasing tools capable of cutting sheet metal. Try to put back in the spot welds wherever they were located, such as the floor joists, or the back sides of the rockers. be sure to cut away the old rust, and overlap the new panel over the old one about 3/4 inch. I personally like to plug weld in floor pans, meaning you punch holes around the perimeter about every 1-1/2 inches. You can seam weld, if you prefer. Grind off any paint before welding, and grind the edge of the new pan to be welded. That cleans off any packing oil, or galvanized coating. As far as bending and shaping, that talent just comes with practice and patience. A rubber mallet and a sturdy piece of 4x4 lumber work well, don't try to do bends all at once with this method. Use sheet metal that is at least 22 gauge, 22 is very malleable, yet reasonably strong. Start with a small patch, then tackle the larger spots as you gain confidence and experience with working the sheet metal. Bill