Use on any 608 bearing Fidget Spinner!
This is a remix of Travo's Penny Adapter for Fidget Spinners (http://www.thingiverse.com/thing:2254960). Like Travo I hate the idea of wasting money on 3 extra bearings that are just used as weights - even cheap bulk bearings cost 15-20c each whereas these weights come in at approximately 2c of filament (and 4c of pennies)!
I didn't like the open look with exposed pennies (or the possibility of them flying out) so I modified their design to include a top and bottom layer. The design is intended to be paused at approximately 6.4mm so that you can insert 4 pennies (US or Canadian) then resume the print, sealing in the pennies and creating a very nice 10g weight at exactly 22x7mm (same as a 608 bearing), perfect for your favorite Fidget Spinner.
I've included the GCode file from my Maker Select Plus (same as the Duplicator i3 Plus) that includes the pause at the correct height.
The design was also inspired by Malcolm3DPrinting's Enclosed Penny Spinner : http://www.thingiverse.com/thing:2303216
Monoprice Maker Select Plus
Pause at approximately 6.4mm to insert pennies, then resume. Make sure pennies are inserted fully so the nozzle doesn't catch (I haven't had this happen, but just covering all the bases).