Somewhat pricey but nice to work with

I've been using a sheet material often used for signs that is 'friendly' for prototyping and permanent project components. It's rigid, light weight, easy to cut, drill and shape and quick, strong joints can be had using ordinary pvc cement; it's available in various thicknesses (I like to use 6mm). It's foam pvc board. The last price I paid for a 4'x8' sheet was around $50. - Scotty