First method is basically dismantling the sweaty confetti mod you can get from Xur's Treasure Hoard
Second (0:45) is Get Banshee's Gunsmith Bounties and just do them in Shattered Throne Thrallway it takes less than 5 minutes. You can get the thrallway checkpoint easily by either opening the destiny 2 companion apps lfg section or in any major destiny 2 discords lfg section or hey if you dont get one there just leave a comment ill give you one.
From the bounties method you can make about 20-30 a day in less than 10 minutes.
There is a third method where you dismantle blue weapons from collections but i find that more tedious than thrallway method.