I’m glad to hear from you that you have found some books for learning traditional Thai designs.
They are very old & rare books that I have never known before.
A book title: Suksa sinlapa lai Thai by Thongsotsaeng, Mana. Published in 1963 (before I was born).
*Suksa means learning, Sinlapa or Silpa means art or fine art, Lai means design or pattern,
Silpa Pracham Chat Lai Thai, Pracham means particularities or unique, Chat means national.
I had been created a website for teaching traditional Thai designs more than 7 years: www.jitdrathanee.com/Learning
You can send your lai Thai drawings at http://jitdrathanee.com/Learning/sending.htm
This website only Thai version but you can use Google translate (may be difficult for understand the translating -_-).
I had a British member who can read & write Thai http://jitdrathanee.com/Learning/learner/spencer_001.htm
He lives in Singapore as a tattooist.
If my English have better more than this, I will talk to you more.