Ally is easy to work and looks trick with but suffers from work hardening under repeated stresses and cracking and eventual failure is a common and annoying result.
To get around this you need to fabricate using thicker material than you otherwise would out of steel.
In this case, its not that much easier to work with. Having said that, ally angle is extruded with few stress raisers and is often a bit thicker and pretty tough at the angle itself.
I think I would tend to use something a little beefier than 3mm (1/8"), say 6mm (1/4")

Good luck with it.

L8tr
E

Aluminium could be used, however it depends on the type and the temper. Aircraft are made from aluminium (amongst some other things but you'll find it tough finding titanium)
To cut a long story short tasssupervee is mostly right because you wont find any aluminium but your garden variety soft aluminiums around. but certainly 3mm is way to thin for that use.

Not being an enginr or nuffin, I'd say that 3mm is a bit thin. if I was making it with store bought grade aluminium I would go for at a least 6mm.:thumb

my god he's changed his name

Bwaaaaaahahahahahahahah!