12mm ply wood
I now have a whitetooth laser cutter stashed in my garage, with it's 80W laser tube I know it was capable of cutting 12mm laser ply at a decent speed (18mm/s) but I hadn't actually got round to making anything out of it. I decided to break into my pile of 12mm ply by making a very very large version of my marble machine. 40mm wooden balls now roll around a quadruple sized version of MM1.
In other news the double sized marble machine is now available from my shop.