My usual stock storage boxes are formed from box files with foam inserts, with one box holding a single rake of stock.

Annoyingly these will only hold 6 Mk3 coaches, meaning that a rake of Mk3s has to be split over 2 boxes.

Yesterday I found a great solution which best of all was free! Wine crates. Best of all they come full of wine (though sadly you have to pay for that bit!)

The crates that I am using (6 bottle), will each hold 2 full HST rakes of 8 Mk3s and a pair of powercars lieing flat on their side, the width is just a a small fraction wider than a Kaydee fitted mk3 (so there is enough room to get the coach in, but no room for it to move about. I plan on adding a foam covering to the floor/ends (the stuff Bachmann locos used to be wrapped in) along with card dividers between the coaches, along with a second floor so that I can have a base for the 2nd rake to sit on.

Other than that the only modification I plan on making is to fit a set of hinges to the original lid, and reglue the sides into position (given that they are bowing out slightly)