No change to the original model instructions.
The author remixed this model.
I added a slope for all the bottom side overhangs on all of these disks (inside and outside) so that they can be printed and create smooth parts that can be pressed together tightly and work well. The photo shows the parts inverted from the way they are printed, with the original design on the left, and the revised part on the right. Note the smoother surface on the outside edge where the parts are pressed together. That is due to the slope from outside in.