Rivets

[vroom]

How are the Al side panels going to be attached to the frame? Wrapped around the top and bottom tubes?

[Midlana1]

Aesthetically, yes, they'll look best if they're wrapped around. It also moves a potentially nasty "snag edge" out of reach of your pants! The trick is forming the panel around the upper tube so it's a form-fit. If a row of rivets is set on the outside, it makes it easy to hammer the panel around the tube, then anchor it with a second edge. Of course, that's twice the rivets and twice the work. The key is to pre-form the panel over a tube so when set in position, the top edge is already hugging the inside of the tube.

Somewhere I posted I thought it would be cool skin the car in stainless... still thinking about that...

[Poboy]

Aesthetically, yes, they'll look best if they're wrapped around. It also moves a potentially nasty "snag edge" out of reach of your pants! The trick is forming the panel around the upper tube so it's a form-fit. If a row of rivets is set on the outside, it makes it easy to hammer the panel around the tube, then anchor it with a second edge. Of course, that's twice the rivets and twice the work. The key is to pre-form the panel over a tube so when set in position, the top edge is already hugging the inside of the tube.

Somewhere I posted I thought it would be cool skin the car in stainless... still thinking about that...

My first sheet metal project was making a bowl, just to learn a bit how to do it. I used some 18ga stainless because I got some free. It is very hard to bend. Really. I beat the ..... out of it. Barely moved. I switched to 18ga mild and it was like origami in comparison.
Later I used a piece of the SS sheet on a desk I made. It was bent along a leaf spring, then I used the leaf spring as a buck to bend a flange on it. I had to heat it light orange to bang the flange in. Granted the flange was on a curve so it had to be shrunk while bending, but if you want to bend stainless over a tube like you're suggesting with the aluminum, then you're going to feel like a blacksmith by the time you're done. Straight bends aren't so bad, though still harder than mild steel. Definitely would be cool.

[Midlana1]

Oh I know all about the hell called stainless. It's not structural so the only limit on thickness is that it not ripple in the wind, lol. If I use it I'd use very thin material, like <0.020". Regardless, the edges are sharper than sh*t. Everything has to be deburred or it'll grind right through the paint on the chassis tubes.