Depends on the budget, but thin wall (1.2mm-ish) stainless or aluminium pipe split laterally with internal open-cell foam could do the trick. Check your local fabrication shops - they might have some off cuts around the right length. Wouldn't go narrower than 75NB though.
One of these might do the trick: https://skywatcheraustralia.com.au/p...-deluxe-cases/
I use the CASEED120 for my Tak TSA102. Works well. (The smaller CASEED100 would probably work too, but they didn't have it when I first got the Tak.)