The SwarShala Indian music software includes Kappi Mridangam and over 100 other perfectly sampled virtual Indian instruments.
The Kappi Mridangam is very similar to the Mridangam, but used mainly for vocal music. There are 2 varieties of it: one for male and the other for female vocalists, depending on the pitch.
Kappi Mridangam is made of two drum heads, both made of many layers of tight laces. The playing surface of the left head is made of goatskin. On top of these layers are two more layers made of buffalo or cow skin, depending on the availability of such materials.
The right head is made of wood on the inside. The second layer from the first wood is a narrow ring of cow skin, and the purpose of this wood is to bar the first layer from contacting the second layer. The complete circumference of goatskin is crucial for ensuring that the main resonant is placed right in the middle. The outer ring is made of fairly thick cow skin that is half the diameter of the head. This gives an allowance that ensures that the goatskin carrying the black circle is not masked. The black circle at the center is made of a paste made of rice flour and grounded iron ore.
The varying alternating thickness of skin cords used in making Mridangam is crucial as it ensures that musical notes can be adjusted from bass to sharp tones. However, the notes highly depend on the type of iron ore placed in the middle circle.