Ok i might start off with explaining i have never done this before but i hope it makes sense!
This will be filled with pictures along the way to help those who are more visual learners :)
And i should add i cheated and had a half finished pair that is why when you get to the sewn crutch seam the waistband is already sewn :) These i started weeks ago for Hartley his first boardies i should add
First start off by sewing the leg seams, in the shorts pictured there is only a inner leg seam as i like having as few seams as possible next to Hartleys and Baileys legs.
Next step is to turn one leg the right way out:
Then i place the leg that is the right way out inside the other leg and match up the inner leg seams and the tops and bottoms so the crutch seam aligns (second pic is just to show that the other leg is in there!)
Then i sew around the crutch seam, i always sew with my machine first then overlock afterwards (sorry second pic looks odd as i hadnt laid the boardies down properly)
Then tie off lose ends of the threads and turn the right way out
And now all you have left to do is hem and sew the waistband :)
I hope this has helped some newbie sewers!