I would say that the best answer to your question would be a question in return.

What type of kilt are you wanting to make?

"The Art of Kiltmaking" teaches one style of kilt. It is the Iconic kilt as taught at Gordon & Sons.

If you want to make a kilt where the waist fits at somewhere other than the anatomical waist -
If you want to make a kilt from a fabric other than Wool Tartan -
If you want to make a kilt for rugged wear like hiking etc. -
Or if you want pockets in your kilt -

Then perhaps you may wish to look at "The X-kilt manual"
Or The Hand Crafted Contemporary Kilt" when it is published later this year.