In my endeavour to save a bit of paper (plus the fact that I keep losing paper) I try to source as many patterns as I can off the internet or buy them in pdf format. I then save them into a pattern file (which I then subdivide into clothing and quilt or stitchery patterns) so I don't lose them in a computer crash I also then save them onto an external hard drive so I will always have a copy.
A long time ago I started cutting my pattern pieces out of heavy interfacing, so they last a long time.
I tend to reuse the same patterns over and over again, so I find this method works really well for me.
The old dairy asked me where I got the pattern for Thai Fishermans pants from. There are several places on the net but I think I prefer the one from mediatinker.com. Burda also had one but there seems to be some problem with the download of that one.
If you are a larger than life type try taking your most confortable pair of pants folding them in half, back halves together and tracing around the front for the front pattern piece. Trace a centimetre or so outside the pants to give you a seam line.
For the back piece turn them inside out and pull one leg inside the other one (so the right sides of the fabric are facing each other this will give you the curve for the back piece, trace around this.
Then it is a simple matter to cut a rectangle to fit across the top (remember the seam goes on the outside because when you fold it down it will be hidden. You can make this fold down piece a different colour if you like.
There is also a pair of japanese style pyjama pants on that site you might like to try I prefer the loose leg of the fishermans pants better.
If you are new to sewing buy some really cheap fabric or use an old sheet and make a trial pair first. That way you can iron out any mistakes on the practice pair. I make several paris out of white calico and it is very cheap so if you want a white pair you might try that as it is usually 150cm wide so it is very economical you can get a pair out of a metre to a metre and a half and it will cost you about $6.00Aust.
You can even make them in flannel for winter lounging pants.
If you try this pattern let me know how you went.