A simple laser pointer can demonstrate twisted light:

1. Download the diffraction grating pattern from departments.colgate.edu/physics/research/optics/oamgp/gp.htm. The fork at the center of the pattern is what twists the light.

2. Using a photocopier, reduce the pattern to about half a centimeter on a side and transfer it to an overhead transparency.

3. Shine the laser through the pattern, ensuring that the beam passes through the fork, and project it onto a wall a few meters away. The grating splits the laser beam into a row of circles. Each of the circles flanking the central circle should have a small hole in the middle. The holes are a sign that light is being twisted.