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.