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The Tropical Products Institute (TPI), a scientific unit of the Overseas Development Administration, has gained considerable experience in operating transportable metal kilns of various designs both in the U.K. and in many developing countries. The Institute has evolved a kiln design which is considered to be optimal in economy of construction, robustness and durability, ease of operation and maximum efficiency and productivity for developing country situations.

The major features of the TPI designed kiln are:

- 3 mm thick sheet steel is used for the fabrication of the bottom section of the kiln; 2 m thick sheet steel is used for the top section and cover.

- The two main sections of the kiln are cylindrical.

- 50 mm angle iron shelves are used to support the top section and cover. These are welded to the inside of the uppermost rims of the two main cylindrical sections.

- The eight inlet/outlet channels positioned under the bottom section of the kiln are open based. A collar is provided around the hole in the top face of each channel to support the chimney during the kiln's operation.

- Four equally spaced steam release ports are provided in the cover of the kiln.