Formula feeding on the go, tips.

Has anyone some good formula feeding tips for on the go? Right now I prepare the dr. Brown bottle with some water and have the measured powdered formula in a separate container. It is just a bit annoying to mix and prep everything while I'm out.

Disassembly the bottle, take out the anti bubble stick, mix the formula into the water, shake the bottle, put the bottle parts back in and put the top back on. Anyone have a more simple solution with less equipment to carry?