I'd made up some quick temporary fenders last weekend for the remnants of Hurricane Patricia passing through and checked today to see how they were holding up. They're still fine so I thought I'd share for your amusement.
I cut a piece of cloroplast length-wise, about 1 3/4 inch wide, and bent it by hand and heat-gun around a wheel. Then a couple of strips from the fork to the back. A couple of tie-wraps and bits of inner tube to hold it together and:
the rear:
I think I'll leave them on permanently since, as you'll have to admit, they don't really detract from the overall look of the bike.