Heh. In that situation, Iād probably surrender and start putting stickers on them.
Good man Nano!
The possibilities are enticing; do I go with good taste or bad?
I recently bought an inexpensive foam boehm flute case for a friend. I bought the Bb foot size in case I needed the extra length. I carved out and pushed about some of the foam to enlarge the slots and it now nicely holds a pratten keyless. I had some old cloth about to patch up the surgery I needed to do on the styrofoam. It will do and cost about $20.
I also purchased an eight keyed Geert Lejeunne flute recently. It came in a very sturdy zippered foam case with three generic slots.The slots were supplied with decently fitted blocks to hold the pieces tightly. I contacted him about his supply of these when my friend asked about a case. He did not have any to spare but sent me to an Early Music Shop online based in the UK. They do stock them but they were too pricey for my friend. I have wondered why a place like the Irish Flute store hasnāt picked up on these. But likely it is one of those things that has to be bought in bulk from China.
Over the years that I have picked up a number of flutes I have three identical Northwind cases. I accidentally found a Pottery Barn Velveteen gifting wine bag that was a perfect fit for them. So after an Ebay search I have a blue, green and gold bag so I know what flute is in which case. I also carry the case out in the bag which preserves the leather on the Northwind cases. If you want to do the Ebay thing have the seller measure the bag. Some are a bit narrower than others. (these wine bags are too short for pratten cases.)
If I ever have so many Northwind cases with flutes worthy of them that I canāt tell them apart, well, thatās a problem Iād like to have. 
Iām currently in that learning phase where I think Iāve found my forever flute, but 'ya never know. And if it comes to that, I would definitely go for the ābadā stickers to tell the black Northwind cases apart. You want someone to think twice about how demented the owner is, so they think twice about touching your flute case.
Hereās a possibility:
Then northwind cases look great, but it says on their website they make the cases out of Basswood, which is extremely soft, about as soft as pine. Iāve made solid body guitars out of basswood: itās easy and pleasant to work, but it dents if you frown at it. Basswood has a Janka hardness of 410
I kind of think if I was going to spend hundreds on a case Iād want a harder wood, but then itād be heavier. Itās easy to find a block of hard maple in the dimensions needed for a flute case. Sugar maple has a janka hardness of 1450
But making a case like that isnāt trivial. You need routing templates for everything and then youāve got to put the leather cover on; you need to source the leather and then cut it properly and glue it so it stays glued.
Northwind probably has well-considered reasons for using basswood. It may be that there is a longstanding tradition behind it, but here are my own guesses based partly on an internet search: One, as you mentioned, would be its light weight. It is also very stable once dried, and I would definitely want that. Itās also free of knots, resin or pitch, and thatās probably a good idea. While itās true that there are tougher woods, quality basswood is not brittle, so itās probably tough enough for the job as a light weight material, with softness being judged an acceptable tradeoff. Lower-grade basswood is a different matter, and probably unsuitable for instrument cases built to last. I assume Northwind would not use lower-grade, and that difference is probably part of what youāre paying for; suppliers who know the good from the bad have to source this stuff.
For the finished product, I suspect that the leather covering and fabric lining are intended to be as functional as they are cosmetic: being glued down, they would serve to reinforce the caseās structural integrity to some degree; every little bit helps. As to denting, though, I donāt recall any on mine; prior to this thread I didnāt know what the shell was made of, and while I didnāt handle the case with kid gloves, I didnāt handle it roughly enough for denting, either. In any event, I would far rather the case take the brunt instead of the flute. To my thinking, thatās what itās there for. Iām less concerned with it looking like new; you expect some dings and scuffing over time. Makes it look like a veteran.
I just put in a call to Northwind to see what they had to say about it, but no one was available to answer at the time. Iāll try again later.
FWIW, quality basswood is considered strong for its weight; I did some more snooping around, and itās mentioned among the array of woods traditionally used in saddle tree construction. That might tell us something.
FWIW, neither of the two Northwind cases Iāve owned has shown any external dents in the wood under the leather. But then, I havenāt taken them out of the house that often until recently, so itās not a good test.
Regarding protection, the wood shell of the Northwind is fairly thick even at the thinnest carved-out parts. It wonāt move if you press hard on it, which is more than I can say for the cheap plastic pistol case I was using on a temporary basis. The only really protective plastic cases are the thick-shelled ones like Pelican cases, which are very heavy by comparison.
Jim Kiel of Northwind kindly got back to me from an email Iād sent. Reprinted here with his permission:
Hi Jason,
Basswood or linden wood as it comes from the linden tree is a consistently dense light hardwood that works easily without the end grain pullout that most other woods have. That means that when you cut or shape the piece of wood across the grain, it leaves a smooth surface whereas other woods have the grain pull out instead of being cut smoothly. this leaves small holes where the grain has been pulled out. Basswood has been traditionally been used for small case goods as it is consistent in strength through the width of the board, so when you cut a small piece, you do not have to worry if it has the same strength as the piece on the opposite side of the box, so the box is less likely to warp or crack. It also has minimal expansion in heat so that it remains more consistent when temperatures change. And lastly, it tends to have the same density across the width of the board. You do not have the typical harder and softer places where the growth tree rings are. This allows sanding without the ridges you especially find in pine and spruce.It is readily available at most lumber yards and grows in mixed growth woods as opposed to single species managed forests out here in the west. Therefore the foresters are cutting a variety of woods anyway so are more likely to preserve the few Linden trees that are in the growth.
Hope this answers your questions.
He didnāt address the issue of grade (but then I didnāt ask, either; my basic question was, āWhy basswood?ā). But my guesses as to structural stability and tradition proved correct. Itās pretty evident that one wouldnāt use plain, naked basswood for a fine case, because its appearance is bland, unimpressive, and it would show dirt readily - but it makes an ideal substrate.