Another option which may work for you is a shotgun scabbard, many of which are for sale on Ebay. They are also carried on Amazon's internet site. Recently, I bought two of them. Here are a couple of pictures:
https://i.ebayimg.com/images/g/isYAAOSw ... -l1600.jpg
This one is short, for short barreled shotguns. I have attached it, using the Molle straps, to my backpack so that I can carry my spotting scope, a Bushnell Discoverer, on my hikes. The Discoverer doesn't have prisms and is longer than most spotting scopes, and it fits in this scabbard as if it was made for it. The second scabbard I bought looks like this one:
https://i.ebayimg.com/images/g/L4MAAOSw ... -l1600.jpg
Note here that on the closed end, there's the ability to fold up about 100 mm so the scabbard can accommodate longer and shorter shotguns. Many don't have this feature and only work on shorter guns. Also, mine has the double pairs of Molle straps extending over all 4 rows of web loops, not just 3 as shown in the picture.
I'm intending this one for use with a Husqvarna bolt action 45-70 that is very slim and long.
Both types (and others, as well) are available in a number of colors, including black, camo, olive drab, and darker green, among others.
I will note that, if one of these or others look good to you, do your shopping! My impression is that there are only a few Chinese makers who are turning these things out, and the multitude of sellers just market them. So, you can find the same thing priced like gold, or priced fairly reasonably. I spent a long time looking on both Ebay and Amazon, and this was clear.
Another point: I insisted that any scabbard I'd buy would be made of actual woven cloth, and not just plastic that had an embossed pattern, which would not be very durable. Apparently, there is some mill in China that makes stuff called "Oxford cloth" (which obviously isn't made in Oxford! Why can't they just be honest and call it "Shenzhen cloth" or whatever? Everyone knows nothing is made in the USA or the UK anymore!)
Because these scabbards are made for shotguns, they don't work for rifles with a scope. Maybe there are ones that will, but I searched on "shotgun scabbard" and you may have luck searching by other terms if you want something for a scope.
Just for your information -- good luck!