Did you witness anything supernatural? A friend of mine used one several times and swore the planchette(?)moved on its own. It also would use curse words. He ended up being afraid of it and swore he’d never use it again.
The pointer does not seem to move on its own. It moves by forces applied by the users; however, those movements are induced in the users' muscles by the spirits. Initially, the spirits seem to have only weak control over each individual. That is why multiple people must be touching the pointer. Eventually people surrender more control to the spirits, making it easier for them to move the pointer using those people's muscles. Eventually, a well tuned person can be used to move the pointer by himself. (Getting vulnerable.)
We were able to send messages from one board to another even though the boards were separated by about 300 miles. The spirits monitored people in the group at all times. We would get accurate reports about the location of members and what they were doing at the time. The spirits knew things about individuals that had not been divulged to any other member of the group. The spirits pretended to be able to see into the future; but, no predictions turned out to be true.
I think these are, by in large, the souls of dead people entertaining themselves. The danger is that truly evil and powerful entities can exploit your permissive state of mind to attack you. Those CAN AND WILL become an unwanted passenger on your soul. The danger is, YOU don't know the difference between benign and dangerous contacts. They know the rules of contact, you don't.