or just be able to float even though they can't
Also ping tool could be an item without a model, and you could pull it out (nothing happens) then click and it shoots a projectile at the spot that then turns into an emmiter that slowly goes away.
and no i don't thing the beam and cube would be impossible. infact i know how it could be done.
when picked up the cube always rotates a certain way to show the front. make it so if the laser projectile hits the cube, the cube takes it almost like onprojectilehit and fires of the laser in the "front" of the cube. label a certain part a certain way and it should work. the receiver and beam would be easy to create i think