I cut off some of the kid's jeans for the summer weather.
The first pair (boy's light blue) was a 3T length, but fit my little guy in the waist, so I turned them into shorts. I laid a pair of his favorite shorts over the jeans to get the right length, then cut the jeans about 1 inch longer for the hem. I turned them under once, because my machine can only handle two layers of denim, and sewed two lines with a gold colored Jeans Top Stitching thread. The bobbin was white sewing thread. I'm not sure if the fraying inside is going to be a problem, but I plan to use Fray-Check if it is.
The second pair (girl's grey/blue) was just ready for a summer re-do. I cut them about 2 inches below the center of the knee then turned them up twice making a 1 inch cuff that would sit at the center of the knee. This pair of jeans was made out of a stretch-denim, so it was not as thick as regular denim, and I was able to sew through three layers. I stitched once around the cuff with the same gold Top Stitching thread and white bobbin thread as the first pair.
I did have some trouble sewing through the denim, especially through the side seams; my seam ripper got some regular use during this project. I would recommend starting just before the inside side seam so that when you come around to finish the stitch line you won't need to stop after riding over a side seam. (Hope that makes sense :)
They turned out so cute!