My take on the tri-spinner fidget toy.

You will need 4 standard skateboard bearings, 22mm OD / 8mm ID / 7mm Thick

I prefer the Thicker Spinner Body (this is what is in the picture)
Print 2 Center Spinner Caps (I prefer the thin ones)
Print 3 Blank Spinner Caps (These caps go on the bottoms of the wing bearings)
Print 3 Decorative Caps.

Everything is friction fit and should not need any glue of any sort, you may need to trim the shaft of the caps a little with an exacto knife (look at the 10/1/16 update below as to why)

As much as the ball bearings do look nice. I wanted something with a different look and also take advantage of the bearings in the "wings". I ended up making custom caps for the wing bearings with different items that you can fidget with when you're not spinning the main body.

The (non thick) spinner body was originally designed for just spinning with no caps. Once I put the caps on the body it looked thin with the extra thickness added by the caps hence the thicker body was created.

I tried to contour the body so that it good flicking it with your index finger, the other spinners that I found were too angular or didn't feel as comfortable.

Currently the fitting on the bearings in the body isn't overly tight, I can put standard skateboard bearings in and remove them without much issue. It's still tight enough where it doesn't slip.

UPDATES:
9/30/15 Updated the Center Bearing Cap Thin file when I noticed the divot was not completely centered. Updated the Skull Bearing Cap so they fit better.

10/1/15 Got some new bearings (ABEC 9 rated) from amazon today, MUCH faster/smoother and spins easily 3x as long, that's the good news. Bad news is my old bearings tolerances weren't apparently that great. Popped the old caps out and tried to put them in the new bearings and they were a bit too tight. Pulled out the calipers and saw that the measurements of the ID of the old bearings went from 8.00mm -> 8.05mm all of the new bearings that came in today were all exactly 7.95mm. When I tried to remove the caps off the new bearings the tops broke off leaving the shaft in the bearing. If this happens to you use a hair dryer for a few seconds (took about 15 sec for PLA) to heat up the bearing and then remove the plastic with some pliers (DO NOT use your bare hands you will burn yourself). I may put out another set of caps that are 8mm spec and leave the larger ones for people that have larger inner diameter bearing holes.

10/17/16
Added "Spinner Body Bearing Holes Tight" and "Spinner Body Bearing Thick Bearing Holes Tight". The Bearing size is set to 22 mm in diameter, where as the original spinner bodies were slightly larger (22.15 mm diameter) to accommodate for easier insertion and removal of the bearings.

11/18/16
Added some Fallout Themed Caps at the request of MikeHow.

12/21/16
Added the Aperture Science Portal Logo at the request of Jmanisgreat

1/13/16
Added Minecraft Theme Caps at the request of origamimaster

2/8/17
Added Razor Logo Spinner and Cap Variant at the request of MikeHow.

3/7/17
Added First Order Logo Theme Cap at the request of MikeHow.

3/21/17
Added Mass Effect Spectre logo at the request of ruejack. Renegade and Paragon logos upcoming when I have more time.

4/3/17
Added Dragon Logo Cap at the request of Egadzman, clearance has been increased due to the spinner this was requested for, spinner body was 9mm in height, I added an additional spacing to help clear the spinner body.

4/18/17
Added Spinner Body sketched out by MikeHow. MHCustom_Spinner_Body.stl. This is a 9mm thick spinner with the same tolerances as the thick body spinner.

4/19/17
Added Spinner Body sketched out by MikeHow. MHCustom_Spinner_Body_7mm.stl. This is a 7mm thick spinner.