I think I know a way of making an element called: BALL,

Description: Ball, bounces.

It would be a powder that is limited to one particle in the game at a time. It is the size of 1 pixel but apperas like the circle cursor with about 12 pixel thickness. When near another particle it would calculate like ARAY so it would travel in the opposite direction of the particle it touched with its velocity halfed of the velocity before touching the particle. it would still have airdrag and its vy would be constantly decreasing by -0.5 every frame. When it hits a particle slowly it acts like a powder but would gain velocity in the vx in the opposite direction of the powder it hit but would have a constant vx decreasement. If it landed on a single pixel then the vx direction would be random and this should simulate a rolling affect. I hope its possible and mabye even added in pt. Hope you peeps like the idea and I mean it is NOT a moving solid it just looks like one :D