I've only made one so far but still saving jeans for the next couple of quilts. I cut all the jeans into 6 1/2inch squares and I have quite a few shades of blue, plus black, white, and other colors. I used a denim needle, either 14 or 16.
The first denim quilt I made, I arranged my different shades of blue. It was for my grandson who loved trains at the time. I bought a novelty print that had trains, I cut them out and fused and sewed them on every other square of denim, then I sewed all the sqs together. I did not use a batting, the quilt was quite heavy. I used flannel on the back and fleece on the the borders. Next time I won't use fleece. Then I did a large stipple quilting down diagonally in all the squares but not the ones with the trains.
I made it about 6 or 7 years ago and my grandson still loves it even tho he has grown out of trains.
warm quilt hugs, sue in CA