Diy New Long Strap For My Old Watch

When I first bought this watch it had a white strap. Two years later it's worn out I had to change for a new strap. A staff said they only had a brown one which I didn't like it but had no choice.
Later I had an idea why don't make your own strap? I always wanted a long strap watch.

I'm planing to make more in different colors to match my clothes.