How can I make DIY black out curtains?

Here is some info to help you. https://www.sleepadvisor.org/how-to-make-blackout-curtains/

Hoping this helps:

https://www.hometalk.com/diy/living-room/curtains/step-by-step-tutorial-diy-blackout-curtains-for-nursery-or-bedroom-13954477

Make sure to price out the fabric and supplies vs ready made liners. I can sew but ended up purchasing ready mades for far less.

Thank you. This helps.

I was going to do this but then found them at JCPenney cheaper than I could make. They run a lot of specials, I think I paid under $8 a panel.

But if you want to make them you will need the thermal liner and material for the drapes. They will have to be bonded together which is a pain. If I remember correctly, you use heat.