In those days, the mill engines mostly used smoke signals to stay connected. When they could get ahold of writing materials, they'd occasionally send a letter.
That's easy. You close your eyes, or, perhaps find someone to properly blindfold you if you can't resist peeking. Have them take you to the messiest area in the house, and start grasping around for things. The first item you are able to pick up, put in your mouth. Theorize about what color it is.
That's color theory in a nutshell.
Now that one I do know.
If you need them to gather, you shout "here, dummy dummy dummy dummy!" in a high pitched voice. You'll have a gathering(maybe even one or two you don't know). If you need them to disperse, walk heavily, flick your wrists, and say "get, get, get, get!" in a cackling manner. Away they go! It helps if they think you might have food, or if there's a possibility to grant them food, so feeding little bits randomly helps(make sure you scatter it on the floor, to appease their hunting instinct). If you find one that's wayward or nervous, don't look directly at it, but communicate with it in its own language, body facing slightly away as to indicate you're not a threat.