Thanks for making and uploading this. I did make this following your instruction for 0 top layers so that the top of the model isn't closed and made solid. On my print, it looks just like you might imagine - the top layer around the ring is missing, but so is the top that would make this a solid model. But in your photo, it looks like you are getting the last top layer as far as the rim is concerned. Do you know what setting does that?