CNC Dan
Veteran Member
If you have access to a lathe with a collet closer, you could use that to crimp down the ends. I've done it with smaller tubing. Start by just closing down on about 1/8" of the end. Then advance 1/8" at a time. Then go back to the end, tighten the collet some more, and close down again 1/8" at a time, untill you reach the size you need.