This object was made in Tinkercad. https://www.tinkercad.com/things/58iutFGrz4T
Here is a fidget spinner that I designed to make experimentation easy. I'm using fender washers for weights. The spinner can accommodate a variable number of washers. If you print extra nuts you could also change the distance of the washers from the center.
I used standard skateboard bearings. The grease causes these to slow down too quickly so I dropped them in some Acetone first (a quick google search will show you many ways to degrease bearings). I also found they spin longer of I popped the metal covers off. All the YouTube videos I saw for this showed using a knife to do this. Beware you may cut yourself... I'm not saying I did, but...
The nuts and bolts came from Nut Job by Mike Mattala.