28BYJ Cheap Linear Actuator

I make this cheap linear actuator with 28BYJ stepper and try to 3d print the rail on the base to make it less parts and cheaper. The rail length is 95mm.

BOM list:
1 × 28BYJ stepper (1:16)
1 × 2GT-264 timing belt
1 × 603ZZ bearing
12 × 3mm metal ball
6 × M3×6 screw
1 × M3×15 screw
2 × M3 nuts