Also, if the piece moves, does it essential mean someone is intentionally being a jerk and making it do so or is it actually difficult to keep it still?

Here's an old magic trick: you'll need a mark, seated across from you at a table small enough that that you can comfortably reach each other by leaning across. A card table, coffee table or bar is ideal. You'll also need a small collection of objects, not too large to spread them all out in front of you, not much smaller than your hand. A dozen or so playing cards are ideal.

Have your mark pick one of the objects, without indicating which. Arrange them in a line between you, so that you can place your hand above each without overlapping any other. Have your mark hold your wrist loosely as you (slowly) pass you hand over each object. You may have to make a couple of passes, but invariably the mark's grip will tighten when your hand is over their object.

It's the easiest trick I know, and maybe the only one where there isn't actually a trick involved. You just have to create the right mood, and the mark does the rest without realizing it.

Ouija boards are the same deal. You don't need someone intentionally being a jerk to get an answer, you just need someone who really wants to get an answer.