For the briefs, I am attacking them from two angles. I plan on making one pattern from scratch, and another is going to be a modified version of the Kwik Sew pattern. I will see which one turns out the best.
Here is the start of my scratch built pattern. I took a pair of off the shelf briefs, cut them up and laid them flat. I traced around one side.
I only drew out one side, then folded it along the center line and duplicated the one side over to the other side. That way, it will be a relatively perfect mirror. Here's the final piece after it has been cut out. The next step is to actually cut fabric and sew a pair up. Do not cross fingers in hopes of progress pics. ;)
Here's the start of the kwik sew pattern. At this point, all I have done is roughly cut them out from the larger sheets.
And here I have ironed the pattern pieces out.
Next step is to cut the pieces out and draw up a full, one piece pattern on my drafting paper. Remember, only two seams on these briefs. One that follows the butt-crack, and the other that runs perpendicular along the bottom of the crotch.