Introduction: Knex Manual/Motor Gear Box
Step 1: The Base
Yeah, everything else goes on here.
Step 2: The Motor
This section is the motor.
Step 3: A Bit of Support
It's easier if this is just an extra step. If not the next step is too long.
The added pieces in this picture are: 1 green rod, 1 white rod, 1 blue rod, and 1 yellow connector.
Step 4: Moving Gear
This gear shifts forwards and backwards to mesh with either the motor's gear or the manual gear.
Step 5: The Manual Gear
If the motor jams, switch to this.
Step 6: The "output" Gear
The rod is what to connect the turning part to. It could be any size.
Step 7: How to Use (you're Done Anyway)
With the motor facing towards you, if the trigger is left, turning is manual, if the trigger is right, then the turning is motorised.