I’d worry that steel Swagelok might chew up your tubing Swagelok (and others) have insert sleeves for plastic tubes that give the strength to resist the hoop stresses of the ferrules.

BB&F ferrules come in packs of ten, and while serious club tinkerers may have the tools and know-how to install them on their own, it’s best to have your local clubmaker do the custom work for ...