Similar to my "split radial ball bearing M3x6" but with a reduced OD of 34mm! This is the smallest I could shrink the diameter with 6mm balls.

This ball bearing is designed in 4 sections so it can be printed with the raceway of each section facing up for a smooth surface. The ball bearings are assembled between the top an bottom sections so there is no need for a hole and plug.

Assemble with 6mm Airsoft BBs and M3x6 socket head screw and nuts. 

raceway diameter = 13mm
outer diameter = 34mm
height = 10mm
gap = 0.5 mm

material PLA
print settings: 0.10mm DETAIL
infill = 25% gyroid
seam position = random

bed temp = 70C 
enable ironing, topmost surface only - ironing only enabled on single part prints, not on 4x print.

model available at: 

https://cad.onshape.com/documents/7e17ab9919343800c11cb68d/w/3ffb674873e293654d7a7e5f/e/4e8b510195d668486f6ef4d2?renderMode=0&uiState=67bc2ea6fd9b866452c735a0