I tried to straighten the wadded-up PTFE tube mess (bowden tube) that was shipped to me from China. The heat gun will work for short pieces, but overall, it was ugly. So I wrapped it around a spool, placed it in a sink with hot water, then ran it under cold water. I unrolled it, dried it off and blew the inside out with canned air. I found a bunch of manufacturing oil in it, so be aware of this before using. Then I rolled it back up. It turned out pretty nice(compared to the original mess).
For those searching for materials, the keywords are:
3d printer Pneumatic Fittings PC4-M6 Bore 4.3mm For 4mm PTFE Tube connector Coupler (PC4 is the O.D. of the tube and M6 is the thread)
PTFE Tube Teflon PiPe For V5 V6 J-head Hotend Bowden Extruder 1.75mm 3mm Filament ID 2mm 3mm 4mm Part (2mm/4mm is what you are looking for)
Here’s what I used it for: https://plus.google.com/+MichaelBoquist/posts/QbyFjXeZyZn
