These 2 were put together with skate bearings and zip ties. The bearings took about a month to arrive after ordering them on eBay (10x =~$3au). To ensure that they were kept together as tight as possible, I used a pair of pliers to pull the end of the zip tie. Despite my efforts, It is still possible to pop the centre bearing out… but it can be easily popped back into place. The point where the zip tie joins adds a fraction of extra weight to that area, which will cause imbalance and wobbling… this was more noticeable on the 3 bearing spinner but not so much on the 7.
Since my son wanted the ability to balance the spinner on his finger, I decided to create some finger pads using what I had available. On this occasion, I thought some bottle caps would do the trick. Using a box cutter, I carefully sliced off the sides of the bottle caps leaving the top which would be used as the finger pad. I then took one of the sides, trimmed it and squished it together using the pliers… that would then serve as the centre pin for the finger pads. The finger pads were then hot glued into place.
Although I prefer using my hot glue gun for most things, it wasn’t the best solution for this case. On my son’s first try, he managed to snap one of the finger pads off. When I get around to reattaching it, I’ll mix a small batch of epoxy glue instead.