Hi, I love the sound of the violin.  How do you tune a violin?
The violin is a great instrument! It has four strings and is tuned in perfect fifths.
That's neat. What are violin strings usually made out of?
There are many different types of strings that can actually change the loudness and tonal quality of the violin. The tension can also change things as well.
What kind of wood is typically used to make a violin?
I am actually not sure, but the body of the violin is completely hollow. 
How much does it usually cost to have strings put on a violin?
Violin construction and mechanics
A violin consists of a body or corpus, a neck, a finger board, a bridge, a soundpost, four strings, and various fittings. The fittings are the tuning pegs, tailpiece and tailgut, endpin, possibly one or more fine tuners on the tailpiece, and usually a chinrest, either attached directly over the tailpiece or to the left of it.
Body.
The body of the violin is made of two arched plates fastened to a "garland" of ribs with animal
Mandolin
A mandolin ( ; literally "small mandola") is a stringed musical instrument in the lute family and is usually plucked with a plectrum. It commonly has four courses of doubled metal strings tuned in unison (8 strings), although five (10 strings) and six (12 strings) course versions also exist. The courses are typically tuned in a succession of perfect fifths, with the same tuning as a violin. It is the soprano member of a family that includes the mandola, octave mandolin, mandocello