The "harp effect" refers to an arpeggiated or cross-picking fingering technique. By distributing the notes of a melody over as many different strings as possible and holding the fingerings to prolong the resonance of each string, we can create cascades of slurred notes. The idea is to find a harmonious balance of fretted notes and open strings, making sure they flow between each other smoothly. While certain fingerings are painful for the hand due to their stretch, the pain can be overcome by practicing the fingerings to limber up. Please don't "burn" your tendons, take breaks while practicing.
In many instances, the left hand's alternating ascending and descending movement is logical and fluid. Once we've gotten the hang of it, it’s executed in a single gesture that’s coordinated with the right hand. In this fingering, the fingers are mobile and rapid, passing from one string to the next. The left hand, even at speed, is more economical in its movement along the fretboard. The placement of these fingerings helps the player acquire the needed agility quicker, making it easier to utilize "hammering" and polyphony to get the harp effect. Make sure to hold the bass notes during their full rhythmic value as written in the score. In regards to the right hand sequence, make sure not to play two consecutive notes with the same finger, always going in this sequence: thumb, index, major and ring. Try to roll down the thumb on two or more bass strings, especially if playing the sequence on five strings with adjacent bass notes. I hope this study will create more options for developing a new arrangement or composition, and of course, this technique works in standard tuning as well.