I still have a denim quilt I made for my kids when they were tiny, and my oldest is 30. The quilt was made from old jeans and it still looks as good today as it did when I first made it. I cut about 6" squares and backed it with a red cotton print. No batting. I didn't even use binding; I just put the top and back together (right sides together), stitched around it, and turned it. I topstitched diagonally through the blocks with red thread to hold it all together. It was super easy to make and it's lasted through three kids dragging it around inside and outside.

I have a chest of old jeans that I have saved for a quilt. They are great. I would use flannel or other lighter fabric on the back.

I made a denim rag quilt and all of the denim came from the thrift store in the shape of jeans, skirts and shirts. The skinny legged jeans don't supply very large squares.

Yes denim makes great quilts. I just finished one for my son who is a truck driver. Things take a beating in the truck and a denim quilt will last a long time and its cheap to make!!!