Surefire brand V20 (fixed loop), V21 (quick detach loop) or V25 (metal clip) will fit nicely. I have seen a Pelican M6 case that fits the E2D and has space for two spares batteries, but its a bit larger than the Surefires.
I carry my E2O with (old style) KL1 in a "Ripoffs" CO124 case. It is made of nylon, and has a nice metal clip, but has no place for spare batteries. The case also fits the Inova X5 light (if you have any). Costs about $15.00. This should work with an E2D.