Both of these two photos are my experience when I did my practice. I am interested in growth rings , I like people can clearly see it, so I did the first one. Actually that is a piece of wood, I cut them to small blocks, I put some  on the floor and put  some of them on the others , so the growth rings can be seen. For the second one , it is the same reason to take two blocks on others. I just want to find  a best way to solve the problem.