The Stone Path is a building block that you can craft in your Crafting Menu (default key "q") after finding and learning the according rare crafting Recipe for this block.
Only on its top side, this building block has a pattern resembling a large dalle made of grey rock framed with moss. Four sides look exactly like green Grass blocks, while the underside resembles ordinary Dirt.
Recipes can also be learned in player-created Adventures.
In order to permanently add the recipe to your crafting menu (and so it can be carried over to all other Creativerse gameworlds like all rare and store-bought Recipes), this recipe has to be learnt at first by right-clicking on it in your inventory/bag or dragging it with the left mouse-button over your player character model on the right side of the inventory.
The block can be rotated by holding down R (as the default key) and moving the mouse while holding the left mouse button.
To craft 8 blocks of Stone Path at a time you'll need (as of R44 in June 2017)