Ninjaflex success

After extending the Teflon tube and cutting a point so it supported the filament all the way from the extruder, I was still having prints fail mid print.  I finally realized this was happening when the extruder finished taking up all the slack and started having to pull more filament off the spool. Makes sense.  Since it is so stretchy, any change in the tension into the extruder has a big impact on the amount of material extruded.

So, I have come to the conclusion that the only way to reliably print flexible filament is to either:
1) Baby sit the printer during the print and manually pull the filament off the spool as it is used, or,
2) Make a contraption to baby sit it for you.

I chose #2 but was wondering what others are doing.  I didn't see anyone else with such a contraption but I find it hard to believe that everyone else is hanging around baby-sitting the printer.  Does the Bowden setup eliminate this problem?  Seems like it would help since the carriage motion doesn't impact the rate of feed but I would guess it is not totally immune.

Here's what I came up with:

I printed the tire for the drive wheel with Ninjaflex and pressed it onto an ABS hub:

And here's it in action:

Pretty crude, but it works quite well.  What are others doing to print flexible filament?