Step 2: About tonal wood and pickup
Tonal wood: Types of wood with particular qualities which make them suitable for instrument making. Examples are maple and mahogany. I chose the wood of the Jack tree, which is used in traditional music instrument building throughout South Asia.
Pickup: this is a sensor which converts/translates the mechanical movements of a string to electrical signals. "Piezoelectric" and "Magnetic" are two types of pickups.The former uses a property of certain ceramics and the latter uses magnetic fields to detect mechanical motions.
I found an inexpensive piezoelectric pickup on ebay, but you can find good instructions on how to build one on the internet (try the much loved google search). Magnetic pickups are something you may try out if you feel like it.
**edit: a professional electric violin/cello maker "bulmung" (comment is on first page) recommends piezoelectric pickups with the sensor built directly into the bridge. Shown in a picture below.
** surfinbela shared a link to magnetic pickups: http://www.uli-boesking.de/rebo/