Cardboard vs Mechanical Board Sorry to over post, but there has been an issue posted recently that concerns the 1mm cardboard we normally use for bulkheads and formers. Specifically, some have tried to find alternatives because the cardboard warps easily. The solution is Letramax 2000 mechanical board. It is just a tad thicker than 1mm, easily handled by even a tabletop laser. It has none of the drawbacks we associate with 1mm cardboard. It is more difficult to cut because of its density, but that is the reason why it never warps. Even if you cannot afford the laser cut product, if you switch to the mechanical board, your building efforts will be greatly facilitated!