Ridgid 606 Heavy-Duty Instrument Bender for 3/8" Stainless Steel and Hard Tubing.
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The Ridgid 38043 is a two-stage design tube bender that allows bends from 90 degrees to 180 degrees without ever cross handles; lock/unlock with a half-turn rotation of the bending handle.
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Swagelok has the same style. They work great. They have two rollers that contact the tube in a way that doesn't crush the tube.
Alternatively, Cerra-Bend is a low temperature melting alloy. You could fill the area with cuttings and melt with a heat gun. Does not wet to the inside of the tube, just fills it. I've used it in short assemblies I could submerge in boiling water to melt it out. Dangerous to pour molten into a small tube. May spit back, like filling a hot radiator. Wear a face mask and other appropriate PPE.