Yes, you heard it right You can use your old denim in several different ways and make the best out of scratch, they can be reused to make some amazing DIY products. For that matter, if you have a pair of baggy jeans which are no longer to be used further; you can repurpose them by simply turning them into skinny jeans.
Turn baggy jeans into skinny jeans.

This will look amazing and a very great way to use your old unused denim in a creative way, here's how you do it.
Here's How: commatose
Make a denim wreath!

Here’s a super cool and fun experiment that doesn’t require any sewing at all. If you’ve got a pair of jeans that is just totally shredded and there’s no chance at turning them into another item of clothing, you can use the scraps to make yourself a denim wreath.
Here's How: Denim wreath
Convert your old pair of jeans into a chic skirt with lace.

Make an adorable little jean purse.
This idea is so cute and easy, and it’s another no-sew one!
Here's How: Purse

Make a case for your iPod.
An amazing case for their iPod?This Case is designed to hang on your keychain and cover your iPod
You can even add a zipper and a colorful interior lining.
Here’s How: Case.
Make a cute bookmark.

If you're a bookworm then this is probably the best thing for you cos it is very needed once you start reading to remember where you left. This is a simple, fast, and fun project to create a bookmark out of an old denim scrap. The heart shape is amazing, but you can personalize it with your choice.
Here's How:

Design a surprisingly elegant denim necklace.
This necklace with the beautiful denim-and-pearl flowers is quite a sophisticated statement. the contrast between the dark denim and the white pearls is just so adorable you can personalize it with your choice.
Here's How: necklace.

Make a beautiful scatter rug.
make your own scatter rug out of denim scraps. if your pieces are too small and frayed to use for attire.
Here's How: Rug