i want to make a folding clipboard

[tsttm]

there seems to be some very creative & resourceful people here.

I'm looking to making a clipboard that folds in half. Any ideas on a potential hinge mechanism & method of keeping it sturdy once unfolded?

I'm thinking of using pieces of acrylic now that i've discovered my local plastics shop.

it'll be something like this:
http://www.amazon.com/White-Coat-Clipbo ... 688&sr=1-1

I may just buy it if i can't come up with something better.

any input appreciated!