I have made several portable pressing boards. I use them when I teach for guilds, or when I go to a quilting retreat or in my sewing-office for smaller proyects or for a very big project that needs pressing in a small area and I do not want to carry the entire project to the regular ironing board. These are light weight easy to pack and carry.
I used a piece of aluminum laminated insulation board like the one shown below
You can also use blue insulation boards like these
Use a utility knife to cut a piece the size you want
Make sure it is clean, these boards come from dusty places.
Cover the board with two layers of batting