I use to buy large sheets of 1/8" plywood at HL to cut out for fins, bulkheads, centering rings, etc. The HL was much closer than the nearest Hobby Store. Lately, I have found the plywood at my local ACE Hardware store in the crafts section. This store is only a 5 minute drive. So, I've gone from a 90 minute drive to a 40 minute drive (one-way) to only a 5 minute drive.