The main temple is based around a concrete core, with collected bottles used as construction materials. Two types of bottles are used; green Heineken bottles and brown Chang bottles. After the local monks began to collect them in 1984 for use as a building material, the local government sent additional bottles. In addition to the bottles themselves, the bottle caps are used to create mosaics. As of 2009 there were a total of 20 buildings constructed in this fashion; in addition to the temple there were a crematorium, a series of prayer rooms, the local water tower, bathrooms for the use of tourists as well as several raised bungalows which are used as housing for the monks.

The main temple took two years to construct, but as the materials were still available the site is continually expanded. By 2009 there were more than 1.5 million bottles in use in the construction works at the temple site, leading to Wat Pa Maha Chedi Kaew also being known as the "Temple of a Million Bottles". In 2015, it was named one of the ten leading examples of sustainable architecture by travel website When on Earth.

Parenthetically, 50 years ago the Heineken company looked into changing their bottles so that they could be used as building blocks, a construction material. While nothing came of that, the monks found a way.

From this Wikipedia article.