For an instrument to be featured on this wiki a basic set of features that are idiosyncratic should be present. Features such as having an unusual Interface, Sound Quality, Function, Aesthetic, or instruments that have unusual implications attached to existing are taken into consideration. This page is intended to elaborate on these basic considerations. Ideally an instrument should have two or more of the below qualities to be featured on this wiki.

Interface is the way that an instrument is interacted with in order to play. Changing the layout of frets on a guitar, changing the tuning of the strings, or changing the way a guitar is plucked are all examples of changing the interface of the instrument. Not all unique changes in interface qualify for an instrument to be on this wiki. Preferably the change in interface is paired with some other quality that is also unique. An instrument that sounds like an existing instrument but has a significant change in the way that they are played can qualify. Some good examples to think of are the various unusual ocarina and various unique keyboard layouts.

Ideally this is both a change in the interface and pitch, this property only counts as the same thing. A change in the size of an instrument, making it drastically larger or smaller then the standard form of the instrument. If an instrument has a change in size it should be able to play in relative pitch, playing far higher and lower in pitch then the standard form as well.

Instruments that have features added on top of their standard set of properties or have had elements that are unneeded removed.

Changing an existing instrument to be able to play a different scale (especially a non 12edo scale)

Changes in the sound quality of an instrument can come in various forms. Most easily an instrument can have a unique new timbre. An instrument can also have the same timbre as an existing instrument but have a dramatic difference in pitch or envelope. This property is the most important one to qualify to be on this wiki. If an acoustic instrument is generally unrecognizable as any other instrument on a recording then it will qualify by this feature alone.

Being able to be recognized as different or unique based off of the quality of the sound of an instrument alone. The best way to observe this property is to play a long and consistent tone (if possible) and have the tone be difficult to recognize as an existing instrument.

This is the way that a pitch is heard from start to stop. Some instruments have significantly different qualities to the only the start, middle, or end of a sound they make, but may be the same as other instruments on other aspects of there timbre. The envelope as a whole is important because a new instrument may have any moment of the sound it produces be unique (especially the beginning and end) but all other moments of that same sound be familiar. This property is common when changing the way an instrument makes sound (for instance playing a membrane head on a clarinet body)

Ideally this is both a change in the interface and pitch, this property counts as the same thing. A change in the size of an instrument, making it drastically larger or smaller then the standard form of the instrument. If an instrument has a change in size it should be able to play in the relative pitch, playing far higher and lower in pitch then the standard form as well.

Creating a unique function for an instrument is an important quality to take into consideration. Instruments can be adapted to unique functions that does little to alter the physical form of the instrument but make dramatic changes in the way the instrument is played. This is a difficult to categorize as a trait and it is also difficult to use it as a qualifying property. An example of a significant change of function is the air gongs used in Songeh. The physical properties of the instruments is essentially identical to a didgeridoo but the context in which they are played and the expected playing method are very unique, and because of these properties the instruments do not serve the same function, and are not easily mistaken for one another.

A change in the aesthetics of an instrument is a change in the shape, color, material, or overall character of an instrument without making significant changes to the interface, function, or sound of the instrument. This property is not a qualifying factor on its own (think weird guitars).

Making an instrument out of a unique material

painting, or adding additional decorative elements to an instrument.

This qualifying property is for instruments that have had unexpected consequences to being invented. Often these instruments are not very unusual on their own right but have been used as taking of points for very unusual sound qualities. An example of this are sound synthesizers.

An instrument invention that brings with it the obvious qualities to make a far more idiosyncratic instrument. A great example is the Hyperpiano.