Psi wheel

A psi wheel is pyramid-shaped top-like device consisting of a small piece of paper or foil balanced on the tip of a pointed object (such as a toothpick or needle).

Another common type of psi wheel is in the shape of a cross made out of a very thin sheet of metal such as aluminum or brass.

The arms of the cross are anywhere from 1.25 to 2 inches in length and up to 1/4" wide, with a small dimple in the middle so that it can be balanced on something sharp.

This wheel then balances on a sharp pointed object such as a thumbtack, pin, needle, or pen cover firmly planted on a flat surface.

[1][2] An object such as a thumbtack or pen cover can stand on its base by itself, however an object such as a needle will need to be rooted in another stable object such as an eraser, sponge, box, or bottle cap in order to provide it with enough stability to hold the spinning wheel on its tip; one stable design even uses a plastic bottle cap filled with an equal amount of J-B Weld, a quick drying two-part epoxy, to hold a needle of any desired size upright in place.