The method of construction on an acoustic instrument can vary from model to model. In many cases these differences are minimal, other times the model can then create a new line of guitars. Fundamentally, however there are standard procedures. The techniques analyzed in this section refer to a standard common to a majority of acoustic guitars.
We can start by talking about the shape of the instrument: this is normally in the characteristic form of an eight, with two convexes (one upper and one lower) and a concave center. The difference in the dimesions of these three parts is responsible for the tone of the instrument. In fact, while tighter sides tend to emphasize higher frequencies, a larger lower convexity emphasized the bass frequencies.
Another particularity that diversifies one model from the next is the dimension of the instrument. There are many designations to identify the size of the body of the folk guitar. Starting with the Standard (similar in shape and size to a classical guitar), you come to the Jumbo and the Dreadnought (the models with the largest dimensions - see Martin).
There are also guitars with reduced dimensions, like the 3/4 or the 2/4, normally used by children or people that have difficulty playing an excessively large instrument because they have smaller hands.

The wood

The choice of wood is fundamental in the sound yield of a guitar. If the wood is perfectly seasoned (even for years) or oven dried, the instrument will surely have a long life (if treated with care and attention). A guitar made with wood taken from a freshly cut tree, without first being dried or seasoned, will almost surely have bad characteristics, both in terms of sound quality and construction. A guitar made of low quality woods, even if seasoned, will also have the same negative characteristics.
Also if apparently the choice of wood as a material seems full of complications, in reality it is best for many reasons. Besides being pleasing to the eye, wood is surely one of the best materials in the world both for the tone that it gives to the instrument, and for sound. Obviously, as already said, not all types of wood are adapted to the scope. You need to know well the tonal qualities of every panel of wood that is chosed for the construction of an instrument. These qualities, for example, are the resistence and the force of the tension given to the strings, but also the adherance to the various phases of the painting.
The best system of transforming certain parts of wood into what will be the guitar consists of the seasoning of the wood panels taken from the tree. This is done in dedicated areas with good ventilation, so that the wood loses almost all of its humidity. The stability of the wood comes after numerous temperature and humidity variation processes, which can last many seasons. This is where the term seasoned comes from. For better quality woods, this drying system can last many years and, clearly, has very elevated costs.
Actually, the most common system is oven drying. The wood is placed in a low temperature furnace, in order to eliminate the humidity. This process is much faster (a few weeks) and cleasly less costly. The majority of guitars are made of oven-dried wood, even if some manufacturers also prefer to let the wood season for various amounts of time.

The body of the guitar

The body of the instrument (or resonance chamber) is composed of three main parts: the front panel, the side panels and the back . All are joined with a series of counterpanels, while the joints are refinished with decorative threads.
The predominant section, both from a trimbic and visual point of view, is surely the front panel. This can be one entire piece of two pieces combined together.
The best woods to make the front panel are the red fir, the cedar, and the redwood. Many of the medium-low quality front panels are instead made of laminated wood (or plywood), which are nothing more than thin layers of wood glued together so that the grains alternate. This type of wood, more resistant than others, like solid fir, is very rigid and for this reason doesn't vibrate the same way as the woods mentioned above, and don't produce beautiful and mellow tones.

The front panel can be flat or slightly arched. The second case is the better choice, both from a tonic and a structural point of view, because the curvature is more resistant to temperature and humidity variations.
The front panel is held together internally with a series of reinforcing strips called radials, which can vary from one model to the next (another particularity that identifies the tone).

The soundhole allows the flow of air within the body, and around the decorative inlay. The inlay had the double purpose to decorate and to reinforce the junctions of the various parts of the resonance chamber.

The side panels of the acoustic guitar, can be made of different woods than that of the front panel. Both the side panels and the back (or rear panel), are usually made of the same material. One of the best is surely the Brazilian rosewood, but due to its limited availability, can be substituted with Indian rosewood, mahogany, African wallnut, sycamore or maple.

There are two pieces of wood that become one at the base (the point where the neck inserts into the body) using a system called top block, while the oppposite point is connected using a bottom block system. This last system can be inlaid to cover the joints.

The base, however, is part of the system that joins the neck to the body, and is usually made of solid wood, like mahogany, or a block of very resistant plywood.
The bottom, which is usually rounded, is obtained by joining two pieces of wood together and is reinforced in a similar way as the front panel, as in the design.

The neck

While the body of the guitar has the job of giving the voice to the instrument, the neck chooses the notes. The basic construction of the neck is a piece of wood cut in the appropriate form, even if there are necks where the headstock is glued. In fact, this last procedure is actually more common, because there is less waste of material with respect to a one piece neck. The one piece neck, however, has a better sound.

There are two common methods used to join the neck to the body: with a dove-tail joint or screwed. In the first case, common in a majority of acoustic instruments, the end of the neck is cut as in the figure, which forms the male part of the joint, and is inserted into the female fissure cut into the base. The two parts are then glued together.

On the inside of the neck there is a reinforcing bar, that reinforces the neck in a possition opposite of the tension of the strings. In the first models of the neck with reinforcement, the bar was usually made of a small pole (circular section or T-shaped) inserted in channel just beneath the fretboard. Then an adjustable tension bar was introduced, which corrects for the curvature of the neck to therefore find the ideal curvature of the fretboard. The adjustable bar is installed on almost all models of folk and electric guitars. Normally, the reinforcing bar is not present in the neck of a classical guitar.

The fretboard

The fretboard, or fingerboard, is glued to the upper portion of the neck, that has the frets on which the notes are fingered. The woods that are used for this part of the instrument are rosewood and ebony, as well as also other types of dark, very hard woods. Some electric guitars have fretboards made of maple.
The frets are pressure inserted into appropriate slots in the fretboard. The distance between frets decreases as you get closer to the body.
There can also be position markers inserted in the fretboard. The are visual markers that better identify the position of certain frets, usually the 3rd, 5th, 7th, 9th, 12th, 15th, 17th, and 19th.
The fretboard can be flat, as in the case of the classical, flamenco and some electrical guitars, or slightly convex. Furthermore it gets thinner the closer you get to the first fret, where the strings are also closer together, while they seperate as they move closer to the body of the instrument.
The width of the fretboard can instead vary depending on the model. This, in fact, is one of the reasons why someone perfers one type of guitar rather than another. There is only one way to resolve this type of problem: play the various models.