I made coasters using scrap wood. The corners are sanded and all edges are chamfered. They are finished with a clear coat. The material is ash wood. Besides coasters, I think they can also be used as trivets or placed under plant pots. Since they are made of solid wood, they may warp over time. I use them myself, but they haven't warped enough to wobble. The size is approximately 123mm x 123mm x 20mm. They are sold as a set of 4.