This question can probably be answered best with " How handy are you?" :)

The beauty of many store bought curtain rods is the ability for them to be adjustable in length, and many are tension mounted if you wanted to put the rod inside of a window opening (like a valance type window treatment).

While if if you can't find the finishes or the ornamentation you want, sure you could make your own.

I personally would buy one, because the options out there are more creative, then I could ever come up with!

I need to put light blocking curtains on my french doors but the length of the rods have to be 140 inches and the biggest rods are 120 inches, and Im not sure how I can install curtains.

@aasher - depending on what type of rod you are looking for, there are some drapery rods that are available up to 16 feet in length (192 inches) - outside of that, sometimes you can splice together two rods to achieve the length you need.

Either way it sounds like you need a professional installer or a dealer that can order a rod for you.

Thanks for all the info everyone!