I was interested in doing a coins across routine. I have four regular half dollars but no shell. Would a Johnson shell be fine? I don't have the cash to spend for a schoolcraft so I was looking at a Johnson on penguinmagic. I have bobo DVD set and wanted to do a coins across since I think I'm comfortable enough with them now. Also, I hear you need certain coins for nesting but what is nesting? Do you need different shells for different routines?