I went easy with this one, use existing pants, trace around, sew together. done and done.
So I grabbed some pants, laid them out on the side, and drew on my fabric to get two leg pieces.
Sew up the leg sides on both legs, then turn one leg inside out. Place the right side out leg inside the inside out leg, so right sides are facing each other and begin pinning the crotch seams together.
Sew up the U shape crotch and then flip the pants inside out again.
For the elastic waist, I folded down an inch and a half, using that half inch to fold in again for a clean edge. Then sewed a casing. I measured my elastic a few inches smaller than the waist. You don't want it pulled so tight you can't get them on over baby, but not so loose they fall off. Depending on the amount of stretch your elastic has, typically a few inches smaller is perfectly fine to get the fit you want.
Then I used the old safety pin and elastic method to insert the elastic into the casing. Zig-zagged the elastic ends together, and sewed casing closed.
Turn them right side out and love them!
Once again, I chose not to hem these because I was not sure how long they would need to be since baby is not here yet, but also un-hemmed could get us more use out of them, after summer time. I can always hem later after baby comes if I choose to.
Can't wait to see my little man in these. Maybe even with a matching diaper underneath?