I was at Uresco, the Owens-Corning distributor, today and saw a product that I have not seen before. That is half inch thick pink foam. I have advocated using the 1” pink foam for lightweight cabinets but wished it could be thinner. Here it is. Its the best choice that I can think of for lightweight shelves and cabinets. Surely it is as light or lighter than Tricel core, and much less cost. Also, the edges are much easier to finish. Vacuum bag thin plywood or even fiberglass onto the faces. The result is shelves for example weighing only ounces. That is one inch foam on the lower half of the load below.