A few of you asked how I made the reversible shorts below. Here is a tutorial for reversible pants. Once you get the technique for hiding the elastic inside the two layers, you can apply it to anything - shorts, dresses, whatever!
To make pants, sew two identical pairs using any elastic waist pattern you have. Don't hem the pants, and don't do the elastic waist yet.
In the photo above, both pairs are turned right side out. Turn one pair inside out again, and insert them into the other pair.
This means that the seams are all going to be hidden on the inside and when you look in, you'll see finished pants.
Line everything up nicely. The trick to hiding the elastic comes next: You turn both pairs of pants under at the waistband and press. This hides the unfinished seams and gives you this kind of look at the top when it is finished:
One you have pressed both pairs in, you are going to make the elastic casing. The photo below shows the two rows of stitching you are going to make. Sew all the way around one row and in the other row of stitching leave an opening to thread the elastic through. (I find it a little easier/neater to leave a gap in the bottom row of stitching then snake the elastic up a pantleg, but in this example I'm showing an opening at the top of the pants).
See the opening?
Once your elastic is in, close the opening.
To finish the hems, again turn the inner fabric in and the outer fabric in to meet it so that you have a nice cuff with the raw edges hidden inside. Stitch into place.
Wear them rolled to show off the contrast.