I just finished 10 communion sets for Navy Chaplains. They are made of sycamore - much of it spalted. The sizes are not by design, but by finding parts of the firewood that were free of fatal cracks.
I included a few extra bowls so they can decide whether they want to use them for communion for a couple of people at a time or for a group.
The picture of 3 shows my favorites based on wood colors.
Enjoy