So after answering lot of questions about why I am drawing on sketch book paper and a near disaster trying to erase a mistake on my last drawing I decided to build a portfolio. I could not find one that I felt would stand up to being thrown around in my truck. So here are some pics and materials.
3/8 inch plywood, mine was scrap from work.
contact paper for lining shelves
leather scraps or 2-3" webbing
1" webbing with cam buckles, lashing straps from the camping dept. will work
Cut the 3/8" ply wood into 2 pieces 18"x15". Sanded edges. Then covered pieces front and back with contact paper.
Attach leather pieces for hinges and webbing with cam buckles to secure sides. I cut the straps about 3-4" back from the buckle and stapled that to one side. Then used the excess as the strap from the other side and stapled it down. Hammered the staples flush so they do not stick out.
Finally took some more 1" webbing for handles and stapled down.
Worked great on my last trip. I am going to make it in a smaller size also. Hope this is helpful. Let me know if you have any questions.