One day I was looking for pictures of Brownells XM177E2 Retro AR-15 and came across this posting on ARF.COM.
The metal strapping or banding they're referring to was used all the time when I worked for GM. In Steel Stores where they cut blanks off the huge coils of steel they had to band up the stacks of blanks. Then after they went into and out of storage, a press operator had to break the bands off when the stack was set up in front of the press. A lot of times the guys who banded things up had a cart with a reel of steel band on it, and several clips slid down onto the band, so you could slide one up next to the tensioning tool and slide the free end through it. The tension tool and crimper both sat in the tray at the top of the cart with extra clips. We also had pneumatic combination tension/crimper tools hanging by cables at the end of some lines so the racks could be banded up to keep everything from falling out. That was mainly big parts like floor pans standing up on flat racks with no sides. You had to run a band all the way around the rack and put the free end in the tool, along with a loop of the middle of the band that was still on the cart. If you did it right, you press one button and the motor would whir as the band tightened up, then you hit the other button and it pushed the clip over the band, folded the sides of it over, and crimped it. If you did it wrong, well, there was a whole spool of steel band on the cart, and you could always splice into a band that accidentally got cut off, or whatever. The tools were too heavy to hold up in the air and do that, so the steel cables had them hanging from the rafters at the right height. Signode says some of them are 18.1 pounds, which doesn't seem like much until you hold it about shoulder height in front of you and fight to keep everything straight while you use the tool, then do it again 2 minutes later and keep doing it all day.
If you bought a band of steel and had a hydraulic press set up to punch one hole and cut the band off, you could make hundreds of commercial stock/mil--spec tube adaptor shims cheap and sell them a bunch. The NcSTAR VISM shotgun stock adaptor I would use if I made my VRF14 into a SBS is the size of a commercial stock and I don't know if a mil-spec stock would even go on it.
https://www.signode.com/en-us/