I'm referring to the way he strums when he plays double/triple stops in his songs, he flicks his palm outward and hits the strings with the back of his fingers. My question to you is, how do you make this technique sound as "full" as if you were to spread your three fingers apart and pluck every string at once? Another part of this question is, how do you stop the strum from sounding too "nail-ey"??

the nailey part is what i like about it

see "too many puppies"

I practiced on every surface but a bass for months. If you smoke (I dont) cigarette packs are good. and slowly but consistently flick out. Start from the pinky then go to the index and then back again. Soon you'll get speed, consistency and if you can incorparate your thumb into the mix, its a simple but impressive technique.