flexible MDF...you have 2 options...if its not for heavy work, you can use what i have here which is basically 6mm (approx) thick MDF which has been slit on the back surface allowing for the bends....or it its heavy work, you can use the like of 12/15/18/25mm etc thick wood and slit all along it to help it bend

jammers - You can do but it will be easier to fiberglass the dash start off with a MDF template etc build everything how you want it...wrap it in fleece, resin, strengthen, smooth, and many moons later, you will have a dash LOL! Ill be doing some dash builds soon if you want me to put some pics up

bassboy