This has been suggested a few dozen times. I will explain this the way Skylark spelled it out.

There's two ways to implement "real" moving solids in the game.

1. Have flags for which particles are connected to other particles, so objects can link together their velocity and etc and be separate from one another, at the same time.

2. The exact same thing, but allowing rotation, so that groups of particles can swivel around and the edges have placeholders and etc, which is a lot more complicated to implement on TPT than just simple solids, but is still possible. Other particles could generate a collision field using another grid like for ambient heat and air that permits or denies movement of solids.

It's not as simple as increasing pixel size. Stop suggesting random ways to get it done, we already have a bookmark on this stuff. :P