Our bedroom closet was a DIY special from the previous owners of our home. We had upgraded the closet but were left with a dilemma - the door opening was not a 'standard' size. The two options were to purchase custom built bypass doors ($$$) or to live with the tension rod and curtain we were using. I came across this plan and after a few quick seconds we had decided we were going to try to build our own.
We followed the measuring instructions to measure our door (which we found (not surprisingly) was out of square which made things interesting) and set out to find our wood. My wife fell in love with this wainscoting at Lowes and that became the backing for the doors. We had to buy an extra piece so that I could ensure that the lines in the wainscoting matched the entire length of the door (we used 4x4 sheets rather than 4x8 because our Lowes didn't have full sheets of this particular wainscoting). The wainscoting backing gave it extra bulk and rigidity, making for extremely solid closet doors.
Everything came together and in one week (building and polystaining) we had the doors.