Wooden body (Koddu, Kudam, Koodu or Arada) of the Miruthangam can be made from five kinds of trees. It is collectively known as “Pancharatna trees”. They are Pila maram (Jack tree), Thengai maram (coconut tree), Vepam maram (Neem/Margosa tree), Santhana maram (Sandal tree) and Karumkali maram (Blackwood tree).
The most preferred wood however is “Jack Wood” as it is more fibrous in its structure, has less pores in it and also that, it is not affected by climatic changes (if seasoned).
If the wood is affected due to climatic changes, the Miruthangam will have an undesirable effect on Pitch and sound. The wood must be selected with care. There should not be any holes, cracks, joints or small round plugs called “Suzhi or Mokku”. The tree must be ripe and well-seasoned. Only seasoned wood will withstand climatic changes.
Moulded leather called Mootu hold the leather components of the Idanthalai (Left head of the Miruthangam) and Valanthalai (Right head of the Miruthangam) together. For this reason the heads are generally termed Mootu.
Both ends of the Mootu are held around the wooden body (Koddu) with leather straps (Naar or Vaar). In some modern Miruthangam these are replaced with either high working load rope or nut and bolts.
There are three layers on the Valanthalai or Vala baagam (right head of the Miruthangam) of the Miruthangam. The leathers are made of Goat and Cow skin (Cowhide). The layers are bound together with leather straps to form the Mootu.
Udkara Thaddu, is made of goat skin and is not visible outside as it is placed below the Koddu Thaddu. This layer is like a ring with the hollow centre and has direct contact with the wood. This allows the outer two layers not to make contact with the wood enabling it to produce soothing pleasant vibrational sound (Natham).
Koddu Thaddu, also known as Chaapu thoal, is made of goat skin and is the inner layer that is partially visible.
Veddu Thaddu, is made of Cow skin (Cowhide). This layer has a hollow centre and is the outermost visible layer.
In addition to the three layers the right head has a special black patched area known as Soru or Saatham. This black patch is fixed firmly on the Koddu Thaddu and is responsible for producing “Chaapu Natham” i.e. the tonic pitch of the instrument.
The Soru is a paste made from a mixture of ultra-fine powder of iron ore and manganese oxide and is mixed with Tamarind and cooked rice to a particular proportion. This is usually three parts of powder and one part of cooked rice. This proportion varies depending on the status and quality of the powder. It must be mixed in such a way that the black patch paste is neither too gluey nor dry.
After applying the paste, it must be dried inside a dark room for at least two days and must not be exposed to sunlight. This will allow the paste to dry naturally and the mixture to equilibrate on the Koddu Thaddu.
Once the Soru has been applied and is dry small pieces of stick or manganese granules (depending on the type of Miruthangam) are placed in between the Koddu Thaddu and Veddu Thaddu to enhance the Natham.
There are three layers on the Idanthalai or Ida baagam (left head of the Miruthangam), also called Thoppi of the Miruthangam. The leathers are made of Buffalo and Goat skin. The layers are bound together with leather straps to form the Mootu.
Two layers of Veddu Thaddu, is made of Buffalo skin. Both layers have a hollow centre and is placed one on top of the other. Only the top ring is visible.
Thoppi, is made of goat skin and is the inner layer that is visible through the hollowed area of the Veddu Thaddu. This layer will have contact with the wood, producing “Thom” Natham. A non-permanent paste made of Ravai (Semolina) is added at the centre to produce pleasing base sound.