Earlier I already described the constituency system for the general elections held on December 23 last year. Thanks to a fellow Wikipedian I have now found the announcement in the Royal Gazette defining the boundaries of the 157 constituencies.
The constituencies are based on the provincial subdivision, there is no constituency which covers area from more than one province. 31 provinces have just a single constituency, of which four (Ranong, Samut Songkhram, Singburi and Trat) elected a single MP, 10 sent two MPs and the other 17 the maximum number of three MPs. The remaining 45 provinces are subdivided into more than one constituency, the maximum of 12 constituencies is of course in the most populous province Bangkok. In most cases the constituencies only contain complete districts, just in Chon Buri, Nonthaburi, Surat Thani, Nakhon Phanom, Chachoengsao, Pattani and Rayong it goes down to subdistrict level. Adam Carr already has put maps which all the constituencies on his election archive website.
As usual I have compiled the data into a XML. Anyone who want to add the full results and candidates of the election and the by-elections after the red and yellow cards in that XML? Sadly there does not seem a single such announcement for the earlier elections, so I'd need some help to create a similar XML for the earlier general elections.