1. Arranging of the keyboard

IT (In Tuningland) is arranged on an ordinary  keyboard, I take  the starting point in C major. 
This setup I mark with a color like this: C. 

I  make 3 rows of pure (or nearly pure) fifths. The pure major third in a triad will be found in the row below a fifth and the minor above.

The unusal thing here is that we have two pitches of D. The highest is on the Eb key.

You will not find G-D-A in a row here, therfore Dsus4 is a problem.