a cube of iron is solid. If you release it, it fals. Wy are solids magicly floating in the air in powder? Maybe that would be an idea for the powder toy. So you have to set a wall (that keeps standing like the solids now) so the solids can rest on them. Maybe there can be a group of elements with a new form of solid or paste. Like for example pudding that bounces back up, or paste you can deform under pressure but then stays in that form.
RAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAGE..... DO NOT SUGGEST MOVABLE SOLIDS. They have not been made and probably never made until the C++ remake is done.