Karnatic is never for Dummies. But, it seems to be possible to build a 'Karnatic Keyboard' where ragams (not all) can be configured which helps the musician to concentrate more on the sequcencing of notes rather than on keying correct notes.
To demonstrate this, take a yoyo ball (it is heavier and rubberized) roll it over the black keys(half tones) of a $10 organ. Depends on how you view it, you are playing either 'hindOLam', 'maddhyamaavathi', 'mOhanam', 'udayaragam', 'suddha-saavEri', or Sreeraagam. All these ragams have the note frequency difference sequence 2 3 2 2 3 in clockwise loop. Rolling the of the ball will natuarally be karnatic style because adjacent notes with the 'gamagam' are used a lot in karnatic. You can also Westernize it a bit by taking the ball and dropping it on a little far off (5 to 6 keys) black keys frequently.
In order to play a different ragam other than 2 3 2 2 3 sequence pluck out the black keys and arrange them in a different fasion.
To recap - The Ragam notes are:
0 - S
1 - R1
2 - R2, G1
3 - R3, G2
4 - G3
5 - M1
6 - M2
7 - P
8 - D1
9 - D2, N1
10 - D3, N2
11 - N3
12 - S
So the Karnatic ragam construction rule can be simplied as follows:
First fix note-0 (Sa), note-7(Pa), note-12(high Sa). Then choose 2 notes from Notes1-4. Call the first one Ra and the second Ga. Then choose one note from Notes:5-6. Call it Ma. Last choose 2 from Notes:8-11. Call the first one Dha and second one Ni.
Then total possible number of ragams will be: 4C2 * 2C1 * 4C2 = 72.
Ragam list 2