Luang Pu Yaem of Wat Sarm Ngarm, Don Thum, Nakhon Phathom
Being the direct disciple of Luang Pu Tae Khong Thong, His Guman is the most trusted among devotees all across Thailand and Asia. The correct "making" of Guman involves true knowledge of necromancing and only a handful of Masters truly possess such deep knowledge. Guman is a slightly complicated knowledge that most stuff you read out there are utter nonsense.
Guman is worship at home for protection of homes and family and worship in business places for bringing in more businesses. Simple as that. Stop reading ridiculous writeup.
Of course, most Guman comes with a simple Katha of invoking and simple worship methods. Nothing of those complicated nonsense written everywhere.