I have already made a few by using my wife's 3-D Dental Scanner and then printed them out using her 3-D Resin Printer, but unfortunately while the rendering is amazing the model material is hard as glass. And well enough said. Not to mention they already have the backing if the folding hook was eliminated strap slots could be milled into the raised portions. Less any modifications to depth of ED between strap slot and surrounding supporting materials to support the weight of KAL II supported be strap.
But the best thing about having the ability for a removable backing that is attachable to a strap is you can then also use it as a spare battery ammo belt. You can have multiple lights and batteries attached add not worry about dropping one 100+ ft to the tarmac or hauling 3 or 4 maybe 6 or 7 batteries through an entire winged fuel cell after bucking rivets for 3 hrs, cause now you can't remember how many you came in with that are charged and how many are dead. Especially when it takes you nearly 30-40mins to get into and out of position and there is only enough space for 1 person. The last thing you need is to crawl out with two batteries at a time then have to crawl back in and out 2 more times, that would be over 3 hrs wasted.
If they can be clipped to a strap then batteries can be stationed in clusters and you get them as they are needed and dead one carried out only on the way out and fresh supply in on the return. Then the clusters are simply rotated as required. Std. closed environment safety protocols, aviation, logging, steel work, mining - oil, gas, ore, etc. Really, any place you could thing of where access to the nearest charger is simply just not an option. And every extra battery in your bag is one less tool that would be able to take to the repair/job location, or even worse the bottle of water or food that you didn't bring because last time you had to choose extra food & water or battery and you didn't have enough batteries and now you have to go back.
Otherwise we all just do what we do now and that's duct tape 2 to each leg and 1 to each arm, 1 on KAL II & 1 in tool bag. we go through 6 rolls of duct tape every 4man 3 shift workday & probable waste a total of 9-10man hrs of a typical 96man hr day removing & applying tape to secure extra batteries to make it to were your working. That's just not productive when you think about it @ $30/hr that's $21K /wk in lost production and when you start to look at it like that the $35-$50 Festool could charge I would buy 5-6 for everyone on my crew, cause our bonus on increasing production 252-280 man hrs per month on low side is around $7500 in terms of w-2 wages & $31.5k in Corporate terms of lost potential. IDK.
I know I would buy them and I'm sure once the other 20 Crew Leads found out they follow alone just like they did when we started using Festools and once again, when Juan-Diego (JD) introduced all of us to his CDTB Ritual, (Cuban-Duc-Tape-Battery Ritual). But if not. Oh, Well then. In the words of my young apprentice, JD, "Ju havi better ideas, No. Ok. Then mi, say ju, CDTB shall it be, Viva Cuba!" Gotta Love JD.