UPDATED!!!

2017/07/25: Wow! Sorry I've taken so long and been so quiet (you should see my blog!) but...life happens! I've uploaded the new version of the spool holder that is a single interchangeable piece, so you just print four of them and you're good to go! I put the old version in a zip for safekeeping so Thingiverse wouldn't auto-generate images for those objects anymore. I'll be updating the assembly drawing soon!

Other changes made to the design: Went from inch to metric, so I rounded out the dimensions just a little. And I removed an unnecessary hole that was doing nothing but adding perimeter-printing time.

Previous Update
2017/02/01: I've been meaning to do this for a while, but I've had a lot of projects going on, as part of my return to actively designing for Thingiverse, I'm going to update my first (And very popular!) Thing.

First and foremost, I'm going to remake it in Fusion360, because I'm transitioning over from Inventor. But I'm also going to incorporate the very common sense feature included in dara's remix design; namely, making a single part that can be used as A or B...I don't know how I didn't think of it, I handle lots of items designed like that every day! Don't worry though, that'll be it, it'll be basically identical, just without the need to print two different parts. These are still fantastically simple spool holders, and I still use mine!

Original Text:
This is a spool holder I designed out of necessity back in March, not long after I got my printer. I consider it to be the first 'real' part I made. Print two sets of parts for one complete spool holder. You will need FOUR common 608 bearings, a.k.a. 'skate bearings'.

It uses standard bearings that most Makers probably already have a drawer full of and that makes the spool rotate super-smooth. It's also relatively fast-printing, and you can get away with printing it at as low a resolution as you'd like to make it go faster. (I'd recommend not skimping on infill though.)

It should fit any spool, so long as the flange of the spool isn't thicker than the width of the bearing... And out of 8 different spool types I have, I haven't found one that didn't fit. (Even a mini spool wasn't small enough to bottom-out between the bearings.)