I've read of people using nylon bolts to save weight on bottle cage holders, but it sounds like they break frequently: viewtopic.php?f=3&t=88887&hilit=bottle+cage+bolt+replacement
It seems like titanium or aluminum would be a good option for weight saving (maybe ~3g each, but hey), but how about for those places you don't have a cage installed? Here
is one option from the UK, but I'm not going to pay that kind of money for a simple plug. Anyone know of a "Home Depot mod" that would accomplish the same thing? Would have to be just the right size.