This is from Peter Biffin's website (spikefiddle.com). He is an australian luthier who has desinged a new resonator for traditional instruments. It's very interesting. I suggest you read his approach. 

As for your question about Kamanchehs. In Turkey, Kemence (pronounced kemencheh) is the Cretan Lyra that at the turn of the 19th century replaced the kamancheh. I am not sure about the reason but this happened at the same time the oud was also replaced by the Lavta. The oud made a come back and the persian style Kamancheh is also making a come back, but it is only played in folk music. These kamanchehs are usually called 'kamancha', 'kemaneh' and 'kabak kemane' (made from gourds), and are much smaller but have a very interesting sound, probably because of the skin top. The kemence from kemence.com is called kara deniz kemence (Black Sea) and is played standing up, usually in a group dance. It's popular in Armenia, Bolgaria and the black sea region. The strings are played very fast and in doubles. It's a very simple instrument.

Hope this helps. 

Peyman B.