Stacking the Coasters

The wooden surface here is wide and flat. I found three square cork coasters resting scattered near a ceramic mug. The first step was alignment. I carried the first coaster and positioned it squarely in the center of the grain. The second coaster had rougher edges, but it settled flush on top without slipping. The third completed the stack. Three tiers. Right angles aligned on every side. It is a stable foundation.