Inexpensive closet doors makeover.

With inexpensive materials you can change the look of your boring closet doors. I updated this doors a couple of years ago using aluminum flashing, wallpaper, plexiglass and spray paint. Cut them to fit the inside part of the louvered doors and attach using liquid nails.
Good Luck!

Mariafer.
Aluminum flashing roll from Home Depot, cut with scissors use gloves when cut them. This doors are in my son's room.
Before, boring door.
Plexiglass painted on the back side with white spray paint, use any color you want. I cut them with a dremmel router. Changing the knobs and molding makes a big difference too. This doors are in my office.
Wall paper and dark chocolate paint. 

In this picture you can see the doors in the back.