Nothing saying it has to be on the rifle. You carry secondary gear with you, why not put it on that. Here are some things I make and use. I can make them for others. I figured I was always forgetting my data tables when I'd go to a match but I never forgot certain other items. So, why not start putting DOPE on all those things. I can do shirts and hats too.
Travel mug with DOPE.
iPad case with DOPE & BDC
MTM Ammo Case with adhesive waterproof, tear proof DOPE card
Aluminum water bottle with DOPE
Cell phone case (iphone and samsung) with DOPE
Wrist carrier data cards (waterproof and tear proof)
I make a number of products for carrying data in the field. I don't think of it as a business because I lose a little on every set. It's more of a service to the community.