This is the latest iteration of my key solution. M5 bolt and shaved down nyloc between a chain link. All normal keys fit on the bolt, with a single spacer inbetween (USB requires 2 nylon internal spacers to stop it rattling). and odd keys go on the chain link. It works better for me than Keysmart, or similar, as I don't have to match the depths on each side.
Also recently got a Topeak Ratchet Rocket Lite. I removed the little clamp from the pouch and attached it to my saddlebag, also put the bits in a little box instead of the pouch they come in. The thing is awesome, probably not robust enough to do crank bolts etc, but plenty of torque for most stuff on the road. Would definitely recommend.