Spool holder for TAZ printers

This is a spool holder that provides a nice vertical feed down from above a Taz or similar printer. How is it different from every other spool holder?

* It holds the spool in its central hole, so it is secure and not easily dislodged.
* The spool holder is concave, helping to self-center the spool.
* There are bearings on the spool holder, so that it turns freely (the filament does not have to rotate on a fixed crosspiece).
* It attached on top of a Taz using zip ties, and is tall enough that even large spools do not protrude into the carriage movement volume.
* The actual holder is easily installed and removed, because it has locating cones to ensure that the crosspiece is properly aligned.

What are the downsides compared to other spool holders?

* It requires 2 608ZZ bearings and 2 M3 screws.
* The uprights are relatively large.
* It requires more parts than most.

Print 2x upright, 2x bushing, 2x bearing holder, 1x crosspiece. The given orientations work-- it's not