IMO, the BOA BO13010 is an exceptional value considering the quality. They wont damage a flashlight if used properly and the rubber strap material holds up well. There’s often no getting around having the proper tool for the job. The lesser strap wrenches are easily destroyed in this hobby.
Hopefully, someone else will weigh in with a more economical solution that can take some real abuse, but I have my doubts. Been there, done that…
I got some at local dollar stores several years ago for a dollar, sometimes a 2 piece set like that Sears set for a dollar. Haven't looked lately, though.
After some digging, another strap wrench that seems of a great design is by DMC. They also sell the straps separately, which is nice to know. From your posts, Im guessing that you would get a lot of use from a pair. http://www.dmctools.com/Products/loopless_strap_wrenches.html
You can also google “tool distributors in norway” and see what turns up. Those plastic handled things arent good for much more than opening up tight lids in large glass jars. I broke 2 pairs of the sears ones rikr linked almost right away. Darn those pesky glued flashlights!
If you have a second-hand store (where people bring their useful but old items to be resold usually for charity) or a friend whose weight varies widely (necessitating occasional new belts), you could do what we always did before the “Strap Wrench” was “invented”.
Take an unwanted, solidly-made plain leather belt, either clamp it with Vice Grips or just get angry and smash it in your fist… Sometimes you can pull it tight around the item and fold the two ends back over the tight bight around the item. The only point is to get it to stop slipping. And then apply leverage.
Eventually friction will make the belt stick, and then it’s up to your leverage.
Best lever I’ve found for this is a leftover board with the end of the belt glued and stapled down one side. I get what “feels right”, which is usually 1” (25mm) square * whatever — I like a length somewhat shorter than my forearm, but YMMV.
Cheap, effective, lasts an amazingly long time, and easy to replace whenever you need to. If you focus the wear on a specific part of the belt it’ll fail there eventually but all the rest will still be good… A fat man’s belt could last a lifetime.