Weight

Each item has their own weight or density assigned to them. This affects the piston push limit, boyancy and others. For example: Stone may be more dense than wood, so it floats slower.

The different crafting recepies will be included in this. A log is crafted into four planks and should therefore weigh four times as much.

Pistons will be able to puch more if the blocks are light and less if they are heavy, and heavy objects will rise slower to the surface of water and the heaviest might nt even float at all.

Maybe carrying lots of heavy objects could affect your mobility in some way. You might fall faster, run slower or won't be ale to jump as high, so that you have to think about what you're carrying.