Have you ever looked at "tenkarabum"
The Medium case has a diameter of 1 1/2" and extends from 16" to just over 24". The case will not fit the Daiwa Expert L LL36 or L LL45M, Nissin Oni Honryu 450 or 395, Shimano 34-38 ZL or the Tenkara USA Ito. It weighs 2.3 ounces.
Medium Rod Case - $10
I have several of these and they work fine---IMHO.
I also have a slightly less than 24 " (1/2" + -) old Wright /Mcgill Trailmaster tube with chained on lid.---May be helpful.
I actually have one of Chris' (Tenkara Bum) cases on order to use in the interim. Coincidentally, I bought the rod from him, but this rod doesn't come in what I would call a case. It isn't a particularly expensive rod, but every rod I own (fly, spinning, casting) is in a case. Maybe because my first rod was a Trailmaster
There are options out there from Tenkara USA, but only one is long enough and it is too long. Knowing me, I would want to cut it down and it is carbon fiber & fiberglass and I don't really want to try cutting that down and reinstalling the end plug which I've a done a few times with aluminum tubes.
Like I said earlier, no regular fly rod tube company (REC, Landmark, Clear Creek) makes tubes with a 1" ID or even OD. I know I could fabricate something, but I hoped for something beyond my own abilities in aluminum. However, if everything turns out the way I hope, I got an offer from someone to make me what I am after.
In the meantime, thanks again for all of the suggestions!