Ugh... this is why I don't do school age, anymore.
I have no patience for this sort of thing. I personally would let him know that at this time, we are sitting at the table to do a craft/activity. If he chooses not to do this, that is fine, but he will remain at the table and sit somewhat quietly until the rest of the group is done. If he's bugging the others, being loud or crazy, you implement whatever method of discipline you use.