Wow no mention of DR, they'll do onesies of any gauge and length.
They'll even print boxes with your custom strings and name of the set.
I looked up DR Legends on the DR website, and below the listing for the available pre-packaged sets, there is this statement (emphasis mine):
“Custom sets and singles are available in all of the gauges above through your favorite retailer”.
So are you sure that you can order any other gauge or length? It’d be really nice if you could, since custom flats are really hard to find.