In case you need a cardboard mustache to go with your cardboard lederhosen...
This is pretty straight forward, but I just wanted to remind you to make sure that your cardboard corrugation channels run in the direction that you are cutting your whiskers. I scrunched up the mustache a bit and glued it down to give it a fuller shape, but you can also just glue on more cardboard whiskers one piece at a time to fill in any gaps.
Last I glued a square of cardboard to the back and strung a sturdy rubber band through the corrugation channels, painted my mustache with basic tempera, (you could even use watercolors) and....Voila. Cardboard mustache.
Want a peak at some of the world's most incredible facial hair? Click the link to check out Dave Mead's Magnificent Specimens photo essay. I promise it will make you smile.