Customized version of https://www.thingiverse.com/thing:3020746

Created with Customizer! https://www.thingiverse.com/apps/customizer/run?thing_id=3020746

https://www.youtube.com/watch?v=iV5-AlCLbgQ

Made using the gear_sphere_core_half model (all the shafts printed in place), with stingy option (9 bearings for 18 gears). The equatorial half-shafts printed slightly oversized when the two halves combined. Cut each half perpendicularly with a hack-saw or similar to make a slot. This results in a fairly snug, but removable fit. The other printed shafts were undersized. I coated these shafts with a few drops superglue prior to pressing bearings on, and added more glue to cap it off. The gear then presses onto the bearing once in place. The central shaft hole adds strength (shaft becomes solid) and also allows for insertion of bamboo skewers for reinforcement and expansion of shaft inside bearing. One could also use this hole for M3 nuts and bolts with suitable washers for an extra secure assembly.

Assembly was a trick in itself, left as an exercise for the maker.

Using the following options:

logo = 0
logo_zscale = 1
use_bearing = 1
simplify_gears = 0
slotted = 0
speedholes = 0
trim_gears = 1
gear_b = 1.65
stingy = 1
simp_holl = 1
sphere_R = 50
shell = 2
scl = 1.063
gear_h = 10
bearing_h = 11.5
bearing_s = 7
bearing_d = 8.5
bearing_r = 11
bearing_b = 4
gear_module = 2
gear_twist = 10
mark_tooth = 0
$fn = 48
AT = 0.01
t_segs = 4
g_segs = 4
gt = [17, 20,20,20,20, 20,20,20,20, 20,20,20,20, 20,20,20,20, 17]
gr = [1,4,4,4,4,1]
of = [0,90,180,270]
logo_file = gear_sphere20180811-49-1u9rhp6.dat