titanum is lighter than aluminum...most parts are alloy's....so they aren't as light...cost is problem with it not cause it's expensive but maching it isn't easy. Don't want much steel it's heavy...aluminum is best bet and composites of course...composite frame would be sweet....wet layup maybe 15 ply's be strong enough to drive a caddy on and not break it. Since it's for rc use wouldnt need perfect material either could be past shelf life it'd still bond alright....cheapest way though is using your common aluminum aloy's....6061 and 7075...don't need t6 temper...t3 is more than enough...you could even use 2024 t6 which is fairly cheap....or could use t0 and heat treat when done forming your parts...depends if you got brake's and such to bend or your going to cnc alot. To be honest if your a machinist and going to make parts....1/6th scale buggies are desperate for parts...mainly the xtm/firehammers...we can't get steel gears anywhere in the states we gotta order them in from germany...alotta cost for a single gear so we wait til we're buying $500+ worth of parts....ya can hook me up with some steel pinions for xtm 1/6th scale and steel spur's I'd buy em off ya and can getcha a few lhs's that would also.