Securing aluminum panels for welding?

Anyone have tips or a technique they use for securing aluminum sheet edge-to-edge for welding when you have odd angles or multiple pieces that need to be held together before you lay down some tack welds?

Thanks!

I use cleco clamps

Or these cheap butt weld clamps

aluminum magnets.

wvumtnbkr wrote: aluminum magnets.

Actually, an AC electromagnet can be built that induces current flow (and thus magnetic field) in non-ferrous metals that yield such a beast.

Was a construction article in Popular Electronics magazine in 60's

So after watching many Youtube videos, I've learned something useful. To answer my own question, clamping steel bar stock behind the aluminum piece and then using magnets on the bar stock allowed me to butt the aluminum panels together at the required angles without any crazy jigs or apparati. The steel has a further benefit of acting as a heat sync so I don't blast holes in the edge of the aluminum sheet.

Also, outside corner welds on 1/16" aluminum sheet is berkeleying difficult. I think I may have bit off more than I can chew with this project. Shoulda used steel I guess, but it's just not nearly as cool.