The OTOP crafts market is in Buriram, it is set up basically across from the entrance to the New Taweekit.
If you haven't seen there is bascially a new road across the street from the New Taweekit and essentially follows the Railroad spur to Road 288 (the circle around Buriram).
OTOP used to be set up downtown by the old circle just North of the Elephant Circle. It is a big air conditioned tents with "stuff" supposedly from different cities around Thailand, to include food. The Women love it.