Same here, it is great to have Titanium for certain key components which need to stay rigid and straight like motor mounts.

As for thickness's here are some examples...

Conker 3 - 3.6mm Grade 5 base and top armour to stop axes and spinners.

Little Hitter 3 - 3mm G5 front and 1.5mm G5 sides capable of surviving the most powerful spinners, just.

Mr Mangle - 4-6mm G5 welded unibody, incredibly strong and rigid but exposed top.

Binky - All armour and Base plate 2mm Grade 2. Slopped and able to deflect most blows, can be bend back into shape.

Beauty (1- - Tubular titanium exoskeleton design, can survive spinners but welds break eventually.

It all depends on what you want to do with it. Some Beetles and ants use it as scoops. If its a light event, even with spinners then 1mm of G5 may be enough but if you wanted to come here you may need at least 2mm depending on the design.