Pants are the made the same way, just make the legs longer.
I can make a pair of these in about fifteen minutes. I make a lot of similar things, like ultralight windpants, fleece pants to wear under them, bib foulie rainpants, etc. It's amazing how fast it is to make something like this, which costs big dollahs in outdoorsy stores.
Fine photos by Star
Shove one pantleg sleeve into the other and flatten as seen here.
This will be your pattern.
Step 2: Fold Over the Fabric
Lay it flat on the ground and fold it over as seen here so you can cut out both pieces of cloth at the same time.
You won't accidentally make two left legs this way.
Step 3: Trace the "master shorts"
It doesn't matter how dark/contrasty your marker lines are, none of them will be visible when you're done sewing.
Step 4: Cut Cloth
If you want to copy a pair of shorts exactly you should draw a "sewing line" and a "cutting line" outside that. The "seam allowance" is about a half inch for seams and hems, and about an inch for the drawstring at the top.
If you're making nylon windbreaker pants, you might want to melt the edges with a lighter or "heisschneider" to keep the cloth from unraveling. Plan ahead though, those melted edges can be scratchy.