Metal Control Panel: How to prevent each switch from shorting to metal panel?

Most if not all are isolated.

You will not have any problems. The internal contacts for the switching mechanism are not connected to the external structure of the switch.

Make your panel!  👍🏼

however, I use the metal panels as a ground for other switches that need a common ground.

Some switches use the frame as common. They only have one terminal for each position. They tend to be older and used in dc applications, especially automotive. I have had a bunch myself for decades.... they seldom get used to ever get used up. (ah, a kill switch on minibike, snowblower, etc. uses one)

If you had to, you'd isolated with bushings, fiber washers, and/or fishpaper.

Use a wire holder/knot in wire inside the box to stop yanking from the outside having any effect on switch/wire position/connections inside. 

Thanks for those answers.

Mannyrock