99, I second what Joe just said but would take it a step further. Instead of sheet metal, use aluminum composite material (ACM) to finish it. This is two thin sheets of aluminum sandwiching a polystyrene plastic core, as strong as an equal sheet of aluminum but half of the weight and easy to apply with structural adhesive. There is a tech article I wrote about this in the current July-August issue of Carbuilder Magazine on pages 82-89. It is an online publication, search Carbuilder Magazine. Also, if you check my build diary on YouTube at StricklandRacingInc, you will find more info on construction technique, structural adhesive, and ACM sources.