well you can use a castable foam to make your general shape, but it depends on what you have for a design and what you are trying to mount into this enclosure. If you have pictures or anything I could help you figure out materials and tools to get you on your way.
quick setting casting plastic as the outside, then an expanding foam for rigidity. You will need the display surround so that it can be put into the mold near the end. and you will want/need a donor center consol plug so that everything snaps into the dash.