What are Tumi Ishi Wood Rocks? Tumi Ishi wood rocks are an open-ended wood toy that will provide hours of relaxing, and challenging fun. These handmade blocks are great for boosting focus, and attention, and for promoting creativity Tumi Ishi wood rocks are handmade and unique (no two blocks are the same). The blocks measure approximately 2 to 4 inches, and the weight of each block varies depending on the wood species