ABOVE - This diagram gives you a thorough identification of the parts found in the typical bolt-on neck construction of the modern electric guitar.
If you plan on building a guitar from parts - the parts identified above will help you in making a list of the things you'll need to purchase (or make).
Let's break it down -
THE BODY -
For a standard bolt-on neck build you'll need to decide -
Scale length (the following are the most common - 24", 24.75", 25, 25.5")
Number of Frets (affects the neck pocket depth)
Neck Pocket Depth (determined by the number of frets and chosen scale length)
Neck Pocket Size (2-3/16 or other)
Neck Pocket Shape (Strat, Tele, other)
Number of Pickups (1, 2, 3)
Style of Pickups (single coil, humbucking, etc...)
Front or Rear Control Cavity (Pickguard cover on front or no pickguard cover - there will be a cover on the back of the guitar instead)
Wood Type (there are numerous tone woods used in guitar body construction - they can be mixed and matched such as a mahogany body with maple top - such as the body above).
Finish Type (High Gloss, Matte, Natural)
Body Style (Single Cutaway - Les Paul/Telecaster or Double Cutaway - Stratocaster)
Bridge Style (Fixed, Temolo, or Headless)
Bridge Make (If Tremolo there are different makes with require different body routes such as traditional Fender, Floyd Rose, or surface mounted tremolos such as the Bigsby and most Headless Bridges).
Input Jack Style & Placement (Traditional top jack input, side or bottom).
NEXT YOU NEED TO MAKE SOME CHOICES REGARDING THE NECK -
Necks are just as complex as bodies when it comes to making choices for what it best for your dream guitar -
THINGS YOU NEED TO DECIDE ARE:
Number of Frets - make sure your neck is matched to the scale length you desire! A 24 fret neck made for 24.75" scale WILL NOT work with a 25.5" scale body even if the neck pocket on the body and the heel of your neck are a match.
Type of Headstock - This gets tricky - ideally the headstock you see on most guitars is wrong. Studies in string dynamics have shown that the traditional headstock configuration where the smallest string (typically tuned to "e") should have the SHORTEST distance to the tuning machine from the nut. And the largest string (also typically tuned to "e") should have the longest. Clearly in the photo above this is backwards. Thus the invention of the "REVERSED HEADSTOCK". If you've ever seen a guitar with what appears to have a neck that has been put on upside down - it's actually done for this purpose.
Also there are studies that show necks with headstocks that angle away from the nut are more stable for tuning. Again - the traditional Fender Telecaster headstock/neck above has a headstock design that is in line with the neck's fretboard. Do you want the traditional look/style - which is not as effecient or stable as the modern reversed and angled headstock - or do you want the more modern and functional design?
Type of Nut - Nut materials can be VERY important and whereas many guitarists never really pay much attention to the nut of their guitar - depending on other choices you've made this could be a serious mistake. Nuts are designed to cradle the string as it leaves the headstock and floats over the fretboard. IF you have opted for a fixed bridge design (no tremolo) then the material choice becomes about what is easiest to maintain. You never want the string to be binded by the nut for it could break or snap. Material such as graphite (basically a very high grade plastic with graphite mixed into it), synthetic materials and composites such as Micarta, or natural material such as bone are all good choices. Brass is another choice that can be used and is more common on bass guitars but can be chosen for electric guitars.
If you have chosen a tremolo or floating bridge - these bridges are designed to flex or move - pulling (tightening) the strings thus increasing the pitch of the strings - or they can be pressed down (slackening) the strings decreasing the pitch of the strings. In EITHER case when the strings are pulled tighter or slackened they WILL move in the nut. IF the nut binds or catches the strings when the tremolo is released and the bridge moves back to its "ZERO POINT" (where the strings should be reset to the tuning you've chosen) the string can snap or go out of tune. It is VITAL that the string be able to move freely in the nut OR in the case of a DUAL LOCKING TREMOLO design (FLOYD ROSE) the nut "locks" the strings into a position where they DO NOT MOVE during the use of the tremolo.
A problem with locking nuts is that they are large (deep) and need a "shelf" routed into the neck for the nut to be mounted. Traditional/vintage style necks do not have enough material behind the thin slot of a traditional nut to route and mount a locking nut. This means you cannot take the 40-50-60 year old Fender neck you cherish and put it on a body with a new/modern Floyd Rose bridge because you won't be able to install the locking nut... or can you?
HERE IS A TIP FOR USING A LOCKING TREMOLO SYSTEM WITH A VINTAGE STYLE NECK - There is a clever nut design called a "rolling nut" - it is slightly wider than a traditional nut and has a set of high quality ball bearings mounted for each string to rest on. Thus when you engage your locking tremolo the nut instead of gripping the string (locking nut style) it ensures that the string will NOT bind and can reset back to its original placement. Rolling nuts DO require some widening of the nut slot - but only about 1/2 the width of the existing slot (see below). It's not something that can be "undone" once it is done - so make sure that you are OK being married to the roller nut before you decide to make such a drastic modification to your dream guitar's neck. Or simply have a neck made for you that fits your needs without modification.
Tuning Machines - If you've chosen an "in-line" headstock design (reversed, tilt back or traditional straight, left or right handed) you'll need a set of "in-line" tuning machines. If you've chosen a "side-by-side" design - where three of the tuning machines are on one side of the headstock and the other three are on the opposite side - you'll need a set of 3x3 tuning machines.
ABOUT "LOCKING" TUNING MACHINES - Locking tuning machines are in my opinion a must have - brilliant invention. They simply make stringing the tuning machine simple, easy, and fast. You only need to put the string through the tuning machine's string hole and then tighten the knob on the back side of the machine. It clamps down on the string - removing the need for you to loop or wrap the string around the tuning machine's string peg several times (which often still results in string slippage and stretching). When using a floating tremolo system such as the Floyd Rose - locking tuning machines provide an additional line of defense against your string slipping (thus causing it to lose tune when the tremolo is engaged).
Truss Rod Style & Placement - Another vitally important tool and integral part of a modern guitar neck is the truss rod. The truss rod is a mechanism (consisting of two steel rods) that is inserted through the center of the guitar's neck. It has a "head" where you can turn a bolt (hex head or sometimes Philips head) to adjust the amount of tension the neck is under.
TRUSS ROD PLACEMENT - Vintage truss rods are typically located in the heel of a guitar's neck. You need special tools and you have to remove the pickguard (if the body was designed to allow you access to the truss rod nut). If not it means that the neck has to be removed to adjust it; which is counter-productive since the best way to know that you've adjusted the truss rod correctly would be to adjust it while the neck is on the guitar and the strings are tuned.
Later vintage truss rods were also placed in the heel but allowed for adjustment through a port in the body just below the neck. Still not an ideal location because the strings sat in front of the adjustment port.
Modern Truss Rods are inserted through a port in the headstock and adjustable from the headstock - this making it easier to adjust and tweak the neck's relief without interfering with the strings.
The PURPOSE of the truss rod is to provide a rigid, strong source of counter-force against the force the strings exert on the neck.
Guitar strings are typically made of steel - they are basically small gauge steel cables that when tightened to the point of being tuned exert enormous pressure on the wood of the guitar neck - bending it forward towards the bridge - this is called "RELIEF". The truss rod is designed to counter this force and can be adjusted to compensate for the gauge (thickness) of the strings and other environmental variables such as humidity (wood will swell in humid/moist air and will contract in arid/dry air - this will affect how much any given neck wood will bend or flex under the full pressure of being strung and tuned). The idea behind the truss rod is that you always want to adjust it so that the neck is at "ZERO RELIEF" - the neck is completely flat. This provides the most consistent playing surface.
Most vintage truss rods are "SINGLE ACTION". They have a zero point that is flat and when you turn their bolt they bend opposite the direction of the strings. Depending on the age of the neck and the way it has been maintained, this may not be enough to bring the neck to zero relief. OR - it may be that the neck over time has "warped" in the direction against the pressure of the strings - in this case many guitar techs have reversed the truss rod (taking it out - rotating it 180 degrees and reinserting it) so that it can be engaged to work WITH the strings to compensate for "BACK BOW" - where the neck bends away from the bridge and the direction the strings pull it.
Modern truss rod design is referred to as "DOUBLE ACTION" because modern truss rods have a "zero point" in the CENTER of where their adjustment bolts can be turned - thus allowing you to adjust them backwards or forwards - providing relief or back-bow - without needing to remove them and turn them 180 degrees.
Once you decide on the items above you can start collecting the parts you'll need to build your dream guitar. Over time you may build more than one dream guitar so it will become important for you to start collecting and managing the various parts you've acquired. I keep extra screws, bolts, and other parts (cables, wiring, spare jacks, spare volume and tone knobs, extra pickups, neck plates, etc...) in a storage containers that allow me to separate items out and clearly see them from the top.
You can never be too organized - and never throw away or discard extra parts (screws, bolts, etc...) because when you go to modify your existing guitar or perhaps build a new one - these things can come in very handy.