Cube to pack electronics or just electronic cords?

If just cords-
Grid-it is meant for cord organization and has a stiff board in it http://www.containerstore.com/shop/o...uctId=10028414

The REI toiletry organizers are "cube shaped" with a handle and fairly well padded, though not rigid. Elastic inside will help corral cords and odds and ends. LL Bean makes several sizes of their personal organizer and some are close to the dimensions you listed http://www.llbean.com/llb/shop/51638...#ppMoreDetails , though I don't know how well they're padded. If it can hold full bottles of shampoo, it should be able to hold some chargers.

If you're mixing in small electronics and need more padding-
Check out a neoprene sleeve. Built NY made one for chargers
http://www.amazon.com/Built-NY-Charg.../dp/B000NGWPV8
It is similar to their wine bottle holders or the camera body/lens bag insert.