Hardware you will need
When you are building any type of guitar you are going to need the correct hardware to install on your instrument. These components are generally made out of metal. They can come in chrome, plated gold, brass or plane steel. The material will depend on the quality of hardware you purchase. Below is a list of the essential hardware along with a brief description to get you going based on my experience.
Tuners
Tuners consist of a knob, a worm gear and a shaft. They provide the tuning mechanism for the instrument an without which any instrument would be useless. It is for this reason that it is pointless buying cheap poor quality tuners. After all, a guitar or bass that constantly goes out of tune or that rattles can be extremely frustrating. (remember I said I was speaking from experience!) Some of the best quality tuner manufacturers that I have used are Schaller, Gotoh, Grover, Kluson, and Sperzel.
Bass tuners are heavier and stronger than guitar tuners. This can result in the head of a bass becoming very heavy, especially if you choose to build a five or six string version. To combat this there are tuners available known as hipshot tuners. These tuners are smaller and lighter than standard bass tuners and help keep the weight of the head down. An added advantage of using hipshot tuners is that they allow for a smaller head to be used.
Tuners can be mounted in many different arrangements depending on what your design requires. They can be mounted on one side or else split between the two sides of the head. It is important to remember that there are left and right tuners. This will be important if you mount the tuners on two sides of the head.
Nuts
The nut is the part of a guitar that the strings rest on the neck. The nut guides the strings and keeps them above the fingerboard. Nuts can be made out of various hard materials. Try to stay clear of plastic nuts as they tend to be manufactured cheaply and are generally of poor quality. Some of the best materials for a nut would be bone or compressed bone meal. Graphite or other hard synthetic materials can be very good too.
You can buy a nut pre-slotted if you wish or else you can buy a nut blank and shape and slot it yourself. If you choose to buy a pre-slotted nut be sure to take into account the neck width diameter and the string spacing you require. There are also metal nuts available with adjustable parts that can save alot of work as they can be adjusted once in place.
Neck hardware (only required for bolt-on necks)
Neck plates are necessary in order to attach the neck to the body. Neck plates are usually made out of the same types of materials as tuners. They are generally 3mm thick and 40mm x 50mm. Usually four 4mm screws are used to attach the plate to the guitar which also secures the neck in the neck pocket.
Fret Wire
Fret wire is available in long strips or else in packs of 24 short lengths. Medium sized fret wire or jumbo fret wire is used on most guitars. Fretwire consists of a crown, a barb and a tang.
Bridges
A bridge is the point where the strings rest on the body. There are many different styles of bridge to choose from depending on your needs. The best bridges allow for 3 dimensional movement ie. they allow for the string to move back and forward so you can adjust the intonation, up and down so you can adjust the string height and side to side so you can adjust the string spacing.