Hello Don,
Untill recently I used a rockbag which was ok, but a bit risky as you continously have to watch out that you cannot put anything else on top.
Since a couple of weeks I use a bag made from kevlar with thick foam inside (like flightcases)so you have protction for the knobs.
Flightcases are no option for me due to the weight, so the Kevlar case/bag is an excellent alternative as it is very light weight.
I have no idea or these cases can be found in usa (they are made in Poland) but If you like I can send a mail to the importer and ask him. (just let me know.)
They make any size.

Fred