I've spent the last couple of weeks fabricating and fitting my side panels.
These are made from 1mm ali sheet (1050A H14 grade, which is fairly soft, so easy to bend).
I cut them out with a jigsaw, and bent them to shape using a combination of clamps, lengths of wood, and a rubber mallet.
They're fixed to the chassis using sikaflex ebt and rivets.
They look green in the pics as they still have a protective film on them.
I'm no panel beater, so the finish isn't amazing, they'll be no doubt that it's a homemade car!