In regards to the carbon vs aluminum issue... A complex part made of carbon can be made many times stronger and more stiff than one produced from a single stamped plate of aluminum or even 6al-4v titanium. Take a look at any modern Formula One car...

A proper 1/8 scale carbon chassis is much more difficult to produce than a stamped aluminum or milled billet aluminum chassis. However the part could be made lighter and more stiff... Again, look at the Formula cars...

Dr. Van