4D blocks are almost nothing different to 3D blocks
(in a 3D space, they would look the same),
the only difference is that the 4D block would have a 4thD "volume", that 3D blocks wouldn't have...
There was a video over there that explained this,
the one that showed that 4D Minecraft-like game.
So interacting with 4D blocks wouldn't be such a strange and mysterious experience.