A number of members and companies have made them - Surefire, McGizmo, DSpeck, TnC, Vital Gear, etc. I'm not sure if Vital Gear is still in business, and if that's the case, the only E2C adapter available new is the Surefire piece. Unfortunately, to get the Surefire adapter, you have to buy the LU60A module, or the Scout Light package that includes it.
But there's plenty of E2C adapters out there, so maybe try a WTB post in the Marketplace.