I am a sucker for purpose-built products; it is just so satisfying when something is made for a particular use and designed to fit perfectly. This fender is one of those cases.
The Syncros Fork Fender is now available for ~$13 and is designed to fit perfectly on a Fox fork. While we do not have trails that can be ridden in the mud, it does serve a purpose in Austin beyond keeping the mud out of your eyes: it block dog poop and rocks from making there way up above your moving wheels.
The fender is designed to fit directly onto the top of a Fox Fork. Fox has designed their recent forks with specific mounting holes and an indent that allows the fender to be mounted directly onto a Fox fork.
The fender ships with the screws and Torx tool that is required to mount it directly to the fork. The entire process takes a couple of minutes. There are different models for the step cast fork and the standard fork. To see if this will work on yours, take a look at the fork and see if you have the two mounting holes on the back side of the crown.
The front of the fork has an inset area where the clip of the fender can mount easily.
The one huge flaw in the design is the cutouts near the stanchions. With all of the work that they spent on designing this, I'm shocked that they were not able to do a better design. In my mind if they had actually made flaps that went down along the side of the stanchion they could have protected it from mud and dirt. Instead, the design opens up, leaving the stanchions vulnerable to trail crap. I ride with 2.4" tires and perhaps this is an issue with some of the wider tires, but I would think that it could have been thought through a little better.