I was able to buy a solid core fire door at Lowe's that had the corner chipped off. I got a 55 dollar door for 30 bucks, very flat... I made a large building table with fiberous insulation (like the old cellotex bulletin board sheets) for 40 bucks! Cileng tiles work great but I want to try the drywall method next. I have a smaller building board that is dead flat made out of aircraft grade honeycomb aluminum, it is light and dead flat but only 4 feet by 2 feet, ok for most 40 sized airplanes... I would dearly love to find an 8X4 sheet of the aluminum honeycomb... then I would have am awesome table . I hope to put together a magnetic setup someday. For now I am fine with the old school pinning method of building, it has worked well for 30 years.