Setup instructions and information:
The download will contain two models, a grass model and another optional model designed for leaves.
To create a grass slab you need to place a grass block down with either a transparent block or no block at all below the grass.
Make sure to light up the area below the grass block otherwise the slab will appear very dark if smooth lighting is turned off. You will need to place any slab on top of the grass block in order for players to be able to walk on the grass slab.
To use the leaves model simply surround the grass blocks which are being used as slabs with the leaf block.
Note that the grass slabs in this picture have been highlighted with a blue outline.
The leaves are not required for the slab model to work, but will improve lighting issues pictured below.
The image on the left uses leaves, the image on the right does not use leaves, you can see that not using leaves can render the slab slightly darker.
The leaves model does not render the side of it’s model so they can’t be used in every circumstance, and you may need to switch them out with grass blocks.
This model is designed to be used in custom maps and you are free to use it in your own custom Minecraft maps.