Step 3: Make openings in hobby box

Picture of make openings in hobby box
Openings will need to be made for each rotor head, with allowance for the grommets, and for the switch and cables. I cut a large opening in one side of my box, exposing the entire front portion of the motor including the heads. Then, a large bore hole was drilled into the top for the switch and a smaller hole on the other end for the battery cables.
Your hobby box will be different, experiment with positions to find a nice compact solution.

For clean edges I used a rotary tool, but a hacksaw or sharp hobby knife would also work. These tools are dangerious, so be safe when cutting and wear appropriate safety equipment.