Okay, a bit more specific:
I want the program to have the basic functionality and ease of use of Phunland <http://www.phunland.com/wiki/Home>, but this program does not support magnets. I would like to model magnets of geometries such as that can be created with phunland, and their respective fields. Most important are the operations of electricity and magnetism, and the energy and motion caused therefrom. I need support for varying material types concerning electrical and magnetic conductivity (much as one can change certain material attributes in Phunland).

I want to move and form pieces of differant material types into differant shapes with exact measurements, but the most important attribute is the simulation of electromagnetism - magnets' north and south poles, magnetic induction by multiple varying materials (with at least one material to act as a magnetic shield.), especially to the end of electrical current being produced, and running through a wire. I would like to test magnetic fields, with visual representations, and to test electrical currents as well.