Pumping for scrotal length:
I have been stretching my scrotum sack for about 3 years now using Steel Ball Stretching Weights (I have never pumped - yet!). I currently wear on a daily basis 2 x 3.5inch long by 1.5inch ID Steel stretching weights and have never encountered any medical problems. My sack now hangs some 9 inches from my cock just a few inches above my knees long enough to tie into a knott! Because I am also seriously into piercing I have had numerous done up and down the sack.. The stretching rarely changes when I remove the weights (4.4lbs) at night probably due to the excessive weight over a long perid of time.
Obviously this is extreme permanent stretching that I am very proud of and will continue to wear heavy weights to prolong the stretch. I hope this helps - please let me know how you get on....