I will be moving mine in the coming weeks. I am probably going to use 3" PVC pipe and rubber hose in whatever combination it takes. I want the space where my airbox was for the second battery.
I am putting the rest of the suspension lift on this weekend. If you can wait for pictures I will show you what I end up with.
I have a 3" body lift, so I have a little bit more room to work with than a stock set up. I have a throttle body spacer too, which makes life just a tad more difficult, because it extends the TB out about 1 1/4", making the bend a little tougher.
What I have read, searching the threads on here is that the MAF should be 10x the diameter of the intake away from the TB, now I don't know this to be true and I haven't seen it in any Ford documentation. Extending the wires for the MAF Sensor is no big deal, and choosing where to hook up the crankcase vent hose is not important from all of my reading.
So...if you want to make your own, I would say go get some pieces of 2 1/2" PVC and play around until you find something you like. I would hold off buying your filter until after you decide where you are going to run your pipe. I bought the KKM first, so now I am limited by one more variable I could have controlled if I hadn't been in a hurry.
You can check out the following thread to see what looks like a pretty well made PVC one:
http://www.explorerforum.com/forums/showthread.php?threadid=46074&highlight=PVC