Pym Particle
The Pym Particle is an invention by Dr. Hank Pym. The Pym Particle is a radioactive molecule suspended in a viscous liquid to keep it stable and control energy regulation. This creates an effect similar to a boom tube, the device that lenses spacetime near New Genesis.
The mass and volume of the target are reduced, allowing a grown person to shrink to near microscopic sizes or grow to some fifty feet in height. Secondary controls allow the user to adjust the scale of electrostatic repulsion; this corrects for many of the issues of force over area that might otherwise be encountered, and adjust the mass/weight ratio rapidly as well. Thus, an insect-sized man could throw a punch with a strength/weight ratio corrected even by the q^2 ratio.
Respiration and heat distribution becomes an issue at microscopic sizes. A respiration system and suit become necessary when a person adjusts their height.
Prolonged exposure to the Pym Particle exacerbated Pym's underlying schizophrenic disorders. Other users have not seen a similar effect.