I need advice about presenting my A3 concepts.

There’s this project I have to do which is to do some sketches in 3 * A3 concept sheets.
I have to put the 3 sketches on 3 A3 boards. They need to be neatly presented and mounted on solid card or foam for presentation. Ideally they should be free standing (i.e. able to be placed on a desk vertically for all to see).
They are due 25th of March, so I still have a lot of time.

I’m quite good in building things, so motivation and skills aren’t a problem.
How would you build/mount one of these?
Preferably cheap and simple, please.

Thanks in advance!