I improved the caps to make them easier to hold and to stop them from catching on the bearing. I also made the spinner body slightly easier to print.
I found that the caps were hard to get a good grip on (especially if your print surface gives a glossy finish to the first layer) and they had a tendency to rub against the outer part of the bearing causing friction. I added a concave bullseye pattern on top so that your thumb and finger are cupped slightly and gripped by the ridges. I also added a small raised ring that hits the inner ring of the bearing and prevent the rest of the cap from catching on the outer part of the bearing. These grips make it much easier to hold the spinner and get a good spin without flicking it onto the floor.
The spinner has a small flat area around the three outside bearing holes. This helps with adhesion as the original design has a single line in these areas on the first layer and I had issues with prints coming unstuck mid-print. The extra line gives more surface area for the first layer to stay stuck down.