I didn't know how to construct arpeggios for a long time, I only knew how to get a open chord D shape going and hammering on and pulling off like how Hendrix or SRV would do with pentatonics.
So when I tried to expand my fretmind on my own, I saw that Judas Priest played the arpeggio shredding thing during the solo of Painkiller as pentatonics but playing it as arpeggios, meaning they use the notes in the standard everyone's favorite pentatonic shape and sweeping up and down using just 2 fret hand fingers and right hand muting to execute. In my finite guitarbrain that was a big thing to me. Later I learned too that Eric Johnson sometimes does these kinda things, playing scales more block like then by straight scale steps.
Till today I cant show you a proper 7th arp or a low E string major arp. But I've found many arps straight from the major scale or pentatonic scale. Maybe that could be something you could look at.
