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Novel idea, it really is, but I can't not point out what I believe to be quite a significant flaw in your thinking here. "Are the bearings truly necessary?" ... yes ... entirely. Every video about fidget spinners I've seen talk about either a) how long it spins or b) the centripetal force experienced when tilting the spinner, both of these features requiring a long spinning bearing, something you simply can't 3d print, at least not small enough for a fidget and at least not easily. But I understand your reasoning with not having parts, but honestly you can go to your local skate shop, or zumiez, or any remotely skate-oriented store and pick up a set of 8 bearings for like 18 bucks, and if you own a 3d printer but can't afford 18$ for the parts to make anywhere from 2 - 8 fidget spinners I would be a little bit concerned about how you allocate your money. But do not take this to say I'm bashing your work here, you have made a nice model I might even print one myself if for no other reason than because I like print-in-place models quite a bit, and simply due to its small size it could be fun in its own right, but I would just want anyone wanting to print one of these as their only spinner that this is simply an alternate fidget and in no way a replacement for what everyone on the internet is going crazy over and if you print one to try to see what the craze is all about you will not get the proper experience by any extent of the imagination.