hmmm, sprockets and cranksets are usually forged and then cnc machining used to clean them up. they aren't machined from solid and not entirely sure why you'd want to make custom ones anyway. those could be a little ambitious. dropouts & gearhangers and lugs are probable contenders (though I'm not fully convinced about the latter)

for machining SS or titanium IMHO you'd be better off with a cnc mill rather than a router, as the key to machining hard materials accurately is rigidity but for that you will need something bigger than will fit in a 12 x 8 shed. the machine in the 'sufficiently strong' thread is very good but I'd have my doubts about its ability to machine SS or titanium. SS is 4 - 5 times harder and titanium is 2 - 3 times harder to machine than aluminium.