The grass nozzle worked well really, but the problem I found with coloured butter cream is if you have a lot to do, the heat from your hands can 'curdle' the buttercream eventually. The fat starts to separate out a bit. I can see the sense in putting green fondant through a garlic press, but I'm not sure how you would make it stick to the cake. I did put a layer of green fondant on the cake before I started decorating it, and attached the tiles with edible glue. I think, with hindsight, I should have put a layer of glue round the edge before piping the grass, because although it stayed on, just, as soon as we cut into the cake, it fell off in chunks. But by that time it didn't matter anyway. I hope it will be a long time before I have to worry about it again!