You may like to try to get hold of this book... It's how Sten Rune and I started

"So You're Going to Wear the Kilt! - All You Want to Know about Tartan Dress"
It's by J.Charles Thompson .Published by Lang Syne Publishers Ltd

It has a great starting point for two types of Sporran.

My advice go slow and try everything first with cardboard before you even cut into a piece of leather
Good Luck and most importantly have fun