Unless carefully adult-used (gingerly opened/closed, and lifted over EVERY bump higher than an inch or so) these things fall to pieces.
Many of the old USA-made ones (other than the "bell wings" SUCKING) actually are still holding together (ie. plywood).
I've effectively bolstered some of the USA-made (plywood) ones by "fiberglassing" over the bell wings, but - when the ENTIRE thing is made of masonite - it might as well be made of dried mud.
I'm using TiteBond II and Bondo...
I bought about a yard of Tolex (that crappy black gauzey-papery-plasticish covering), will make (matches the case) long 2-inch-wide strips, glue it over the raggedy corners (after trimming off loose Tolex), add quite a few more 90-degree corner brackets, replace all three hinges and three of the five latches...oh yeah: and handles...
We also had to Bondo over Masonite where the young scholars tore off one of the D.E.G. (big/offset) wheels, so we'll have something semi-substantial to which we can reattach it.
$300 for all of this...but this is THEIR old 186 case, and we're SELLING them a vintage 186 (the one that I've built from serviceable/repairable "vintage" 186 COMPONENTS that I rounded up from the attic) to go into this case. (It turned out to be a REALLY GREAT PLAYING 186 B-flat !)
We're hooked up with OTB, so we didn't have to pay Wisconsin prices for the case hardware...
At the same time, I bought a couple dozen particular-style drawbolt latches (also very reasonably priced) to match/replace the loosey-goosey ones on c. ten of those gray-plastic weird King "box" cases for King marching euphoniums (another school).
After I get it rouged, cleaned, shoot lacquer on it, and assemble it, I'll post a few pics of the 186.
I DID NOT remove EITHER the top nor bottom bows (nor the bottom bow cap), and not even the considerably dented-up 4th circuit tubing...a bit of a "see if I can actually do this, and still have it pass as a REALLY GOOD economy overhaul" experiment...
...It's early 1960's rotors (combined with trimmed-to-fit salvage 1970's S-arm linkage - from my "sack-o'-Miraphone-paddles") is/are REALLY tight/quiet.
I sincerely hope that everyone is absolutely astonished by this oh-so-enlightening post (which I'm offering while awaiting an online payment in realtime, so that I may proceed with paying for a shipping label).
, I stopped off at a school and replaced most of the latches on eight of those gray plastic box King marching euphonium cases (while Mrs bloke got a plastic Fox bassoon fixed up enough to work again...We normally don't do on-site repair work, but this just seemed better than dragging all of those marching euphoniums out to our shop simply to replace latches). On the way home, we stopped and got some 3/4 in. long 1/4 in. thread bolts, some of those lock nuts with nylon in them, and some 1-1/4 in. fender washers for the inside, because I had to Bondo this masonite case where they tore out one of those DEG-style axled wheels, and I'm trying to sandwich the restored material between as much metal as I can manage. I'm sure the young scholars will figure out a way to tear it back up anyway. 
