My eldest was given these shorts in age 9 but he’s not that into them however the youngest adores them. Only problem is he’s a very short nearly 4 year old who still wears some age 2 clothes.
First I got my pattern sorted and measured him to ensure the pattern would fit. I used Domi Joggers which I haven’t enjoyed using before but it was best thing I had to hand for ‘free’.
I cut out the inner net at the waistband.
A few hours of unpicking occurred. I undid the existing hems and the waistband. This allowed me to work with the full width of fabric and the most length. As they had a pocket on one edge I pinned it down. So I could cut safely.
I laid my pattern on top and cut. Now on one side this was easy peasey as it was just print but on the other side there was a picture my son asked to keep plus the pocket. Because of this I had to cut the leg wider than the pattern piece matching the other side.
If you are a regular sewer you will know the front and back pieces of most trousers aren’t the same. I got around this by using the front. I then opened out the shorts and cut away the back to match the back crotch on the pattern. This allowed me to bring in the width a little. The main difference is the back piece isn’t as wide at the crotch area so if you can’t figure this out then just use the front piece.
I also only cut from the crotch to hem leaving the existing front seam to place to save me unpicking to then resew.
As these were shorts and I wanted trousers I had to add extra fabric to the hem. Remember to taper down to match leg pattern. I also added cuffs as per pattern but this depends on your pattern. Alternatively you can add extra waist fabric and less on legs.
To attach the elastic either make a channel or make your elastic into a loop. Place it onto wrong side of fabric at waist. Pin at front, back and 2 sides. Sew into place with zig zag stitch stretching into place. Then fold down and using stretch stitch sew down.
Great tutorial here by Lladybird on how to sew an easy waistband. Alternatively you could so a separate waistband.