For the size I chose 16 x 16 because the range could then be based easily and symmetrically on a center point concerning chunks , while 3 x 3 would I think look better individually when you look at having multiple spaced out they may not be evenly spaced from the border of a chunk if they were 16 x 16 , or at least an even square . Though the idea of them growing seems really attractive as well . Concerning groups I think it would be best if there was a ui associated with the crystals , requiring you to right click a claimed crystal and enter in a password to join the group , or a group could choose to have no password . I would sort of like something that would limit breaking and placing blocks and generally interacting , but I ' m not sure on specifics , but either way optut should be some cost to pay for the ability .