I've made 2 so far and they've come out great and have been fairly easy and cheap.
I used wooden plaques
I painted some acrylic color "backgrounds" on the exterior and stuck some fantasy vinyl decals on them
Then sealed with urethane
Pretty simple, all you need is some paint brushes and I'd recommend marking and drilling tiny pilot holes for the hinges as the screws are very small and you don't want your hinge blowing out.
A simple 3 panel fold design would be to cut one inch off of one of the panels and secure it to the edge of the middle panel to act as an offset when folded.