At first sight, Thai laws are very restrictive concerning foreigners who want to establish in Thailand, but in practice it is quite easy.
You will need to create a legal structure, e.g. a company limited and apply for a work permit. Both procedure can be handle by a local accountant.
For each foreign work permit, your company must employ 4 Thai nationals and its capital must exceed 2 millions Baht. Therefore, obtaining 2 work permits will require THB 4,000,000 and 8 Thai employees and so on.