A good idea – thankyou!
Although my workshop calculator is a cheap arithmetic-only one, the scientific ones staying in the house, I keep and use it in a polythene bag.
I’ve also draped a polythene sheet over the inverter controls on the lathe, and a large “Cellophane” bag loosely over the mill’s DRO. The latter is long enough to cover also the mains switch on the back of the unit, and very loose so as not to impede cooling.
The protector on the lathe’s controls is one of the MEW magazine’s postal bags! It’s retained by a small, wooden tool shelf resting on the chip-tray below the headstock.