Both rings installed on a piston. The rings are dark because of heat treatment.

Note the shoulder on the piston rod, where the piston itself rests. To produce this, I had to make the rod out of 1/2" stock whittled down to 1/4" for most of its length. Have your lathe carefully lined up before doing a job like this: if the rods are tapered, you're likely to have packing trouble.

By the way, the gray background is that little shop-made lapping plate again.