The 4 strings are tunable, with guitar's machine heads tuners.
I use a fine wooden stick to crash into strings.
Each note's vibration go through the wood.
Then you put lips and the side of cheek on the mouthpiece, thiner, so as to let a space for the sound's exit. Then modulations happened at several levels :
breathing, throat, tongue, and lips movement.
(same principle as Jew's harp, with a few options more : bounces, lips and jaws movements).
For exemple with a 4 stringed, I don't play on the 4 strings (although the whole strings were continuously crashed into),
but only on 3 (sometimes 2), the fourth being muffled, either by the thumb for the top's one,
or by the middle finger (or the index finger) for the bottom's one (or the opposite if you hold the Cosmicbow with the thumb at the bottom) each in turn.
That's this alternative movement that give the swaying, and let us go from a linear sound to a rich and complete music.
Between differents rhythms, linkings and playing potentials, there is, with 4 strings, a lot of possible chords, each one leading to a different sound scene,
so that with only one mean of playing, even easy, there is a lot of things to explore.
And with 5, 6, 7 or 8 strings... More !
Each instrument is like a living creature, that means it has his own nature, so the choice of the instrument (too) will direct towards a certain playing type.

TUNING :

If the sound isn't right, either strings are too much or not enough tighted, or the instrument is wrongly tuned.

Tens chords are possible, and each one take us towards new landscapes, sometimes sweet, joyful, melancholy etc...
It is necessary not to neglect to tune before to play, because if the chord isn't well tuned, it's cacophony guaranteed as well.
When you have find a good chord, it's good to save it, either writing it (for ones who write the music or who have got a tuner), or recording it note by note.
It may happen that you find very beautiful chords that don't go within the framework of «written» music,
that's why I think that free ear offer more space than the only one intellect.

For an intuitive simple approach :

You choose the first note on the top low string (following feeling), then you tune the following until it sounds good with the first. To sharpen the tuning,
crash into these 2 strings at the same time (without letting the others sound). Each one has a sense of harmony, of what is beautiful and right...
that's what you have to follow... follow your ear and your heart, and forget intellect with memories and projections, and devote yourself to be listening into present moment.
When the 2 firsts strings are tuned, do the same with the third and the fourth.
It may happen that, on the way, you have to adjust the tension of a string because the instrument could have move a bit under tension of last strings.
As soon as the 4 strings are tuned (or more), check that the bottom low string works with the 2 high-pitched
crashing them simultaneously obstructing the top low string (puting a finger on it), then make sound the top low string with the 2 high-pitched,
blocking the bottom low string. Check by this alternative movement that the two chords of three strings work together ...
here it is ?
So let's go !

MODULATE HARMONICS :

Strings of the instrument take the place of your vocal cords, those are inactive while you're playing.
There is a range of harmonics high-pitched and low, effects and modulations that you can do in turn and/or simultaneously.
The simply matter of talking imply complex movements inside of mouth... Throat's sounds, tongue's clicking on the palate, etc, etc...
including breathing management that is used for breathing in syllables, or projecting letters or words with force...
and many others subtle variations carryied out in an only sentence... We do it naturally, without thinking about it...
The simply matter of talking imply a true mastery of sound, so the idea that we don't know is false.
You have to explore harmonics with your words mastery, even if it's another «language», we all have already a high practice level concerning movements,
modulations and variations of the mouth. Knowing that, you can let falses ideas down because they can block the sound.
To let flowing the sound is something natural as much as speaking. You can aim straight, and crop up in a specific harmonic without have «thinked» about it,
like you speak in a certain tone of voice to express a feeling.
In my opinion, it's important that you follow the melody, the unifying thread, the music; otherwise, you may find yourself in a harmonics soup that have neither rhyme nor reason...

At rhythmical level, you can begin by crashing into strings like a metronome. A simple and regular movement allows to concentrate better on harmonics and melody.
Even if you let sound only three strings at the same time (or two), you always need to crash into the 4 strings. Afterwards, all kinds of rhythms are possible,
that can be improved with sticks bounces off strings, getted by lightly put the stick, then let it bounce off the strings.

To play :

While the thumb touch one of the low strings to stop the sound, you play with the 4 others strings (or 3) making together a chord.
Then, you let go your thumb of, releasing the silent string, and, at the same time, you touch the other low string with the middle finger or the index finger,
going on another 4 notes (or 3) chord. The 3 (or 2) high-pitched strings sound permanently, creating a link between the two chords.
This alternative movement could be played in all possible ways.
With a 6 stringed bow, you can touch 3 strings at the same time (minimum 2), so you play with two chord who have no note in common.
A lot of things to explore !

Handle :



With the 4 and 5 stringed instruments, you can touch one string :


Or two :


With 6 strings, have to touch minimum 2 strings :


And if this position is not right with you, can can take it like that :




The mouth :

Always keep the two lips in connection with the spoon !
Let the body find his best position as well as the place where to pick up the best harmonics.




Here you can see how to play on the Cosmicbow with harmonic spoon... :


Also here :



And for the cosmicbow "classic", horizontal position:

For the right-handed, in the left hand. Two possible positions :
Pouce en haut : ............................................... Pouce en bas :


Mouth position :
Put lips and the side of cheek near the tip of the bow :


The stick :


For the left's hand :
Alternative movement for the position "thumb at the top" :


Alternative movement for the position "thumb at the bottom" :


MAINTENANCE :

Even after 20 years of drying, wood continue to live and to workwith variations in the temperature and moisture.
It is advisable to see to keep (as much as possible) the instrument in an environment the more stable possible.
Avoid to let it close to a heat source, like a fire, a electric heater or in a car in the sun... That is to say,
namely, what makes working the wood is above all dryness of air, that, with heat, drive it to retract. So, a very light moisture in the air is beneficial,
but it's better to avoid a strong moisture like the morning dew...
However, the instrument is treated either with a natural oil varnish who gives a waterproof coat, reducing a lot effect of hygrometry and temperature differences.
When you don't play it, the better is to keep it in its cover, or, for lack, in a thick cloth.
Don't tense the bow too much. Feel the ideal tension, that's makes it sound for the best. Some sound better low, others medium or high-pitched.
If you tense the bow too much, you will deteriorate strings (and resonance effect) especially low ones whose soul is thiner,
those need a relative flexibility to withstand stick's percussions (depending on stick's weight).

If you don't want the wood get dirty and because of the acidity of the mouth and the hand, it's good to put regularly some organic linseed oil,
especially at the mouthpiece level (and better, if you have some bees wax, you can mix it with a few of linseed oil to make a wax cream)
... you just have to put it with the finger, and then rub it with a rag to give it back its brilliance. It lets a very thin layer of oil (or wax/oil), just let dry !
I also make the varnish of the instruments, who is completely safe and natural.
natural oil and natural resins !

STRINGS CHANGE :

You just have to take the old string off, and replace the new one according to the same outline.
If you change the 4 strings at the same time, that is not probable, pay attention not to lose (the) little wood piece(s) that's raise strings,
and replace it exactly like originally, because they are essential for the bow's sound.
If you choose others strings diameter, you may well to find yourself with a bow out of tune, indeed to damage the instrument.

Have a good trip !