I've picked and done one and here is my report:
I couldn't quite make up my mind until the very last minute. I usually prefer ballbusting because I could -somewhat- easily do many in one session but I the other one was more intriguing. I've always wanted to try fitting many clothespins everywhere but I never got the courage to.
I wanted to do something more special and experience how it feel; I wanted to do a Zipper of clothespins and see how painful can it get (I utterly regret this decision now!)
Here is how it went:
I grabbed a lengthy thread and started following the DIY youtube video and made a 12-clothespins long zipper.
I wanted to try it immediately so I got naked and started pinching enough skin for each pin (of 10 pins) on my abdominal area and placed 2 one on each nipple where the end I'm supposed to pull at the one of the nipple pins. See the picture for visualization
(hot picture for attention 
):
After placing those ones I moved to the more sensitive areas; I placed 13 ones on my balls (literally grabbing skin without looking and placing) and another 5 along my penis shaft (all without a zipper)
Now it was the time game, everything before this wasn't painful at all.
[1-2 minutes] were me standing doing nothing but looking if a pin might fall.
[2-4 minutes] I started feeling a little pinch on my nipples and balls building up slowly, I also felt like sitting so as soon as I sat down every pin tensed and started pinching harder so I stood up quickly (was pretty funny in the moment to be honest)
[4-10 minutes] pain was building up very fast everywhere and I couldn't quite decide which are was hurting more.
[10-15 minutes] I was getting tired from standing and started sweating as I tried to minimize my movement to take less pain, ever inched I moved would start pulling on some of the pins, I could feel every inch of the pinched skins. feeling the pain move around, jumping from one pin to the other, I wanted to remove them but looking at clock I felt disappointed.
[15-20 minutes] pain never stopped increasing as if it has no maximum limit, I kept squirming in my place, feeling pins digging deeper in my skin, my nipples are almost numb and my balls felt like a thousand pounds. I was getting shaky and I moved to start my shower to jump in as soon as I'm done. One of the abdominal pins was starting to slip and it pinched much less skin and that hurt like I could never imagine until it slipped and kept hanging by the thread.
[20th minute] I wanted the never ending pain to stop, I grabbed the end of the line and took a deep breath (which actually hurt like hell around my nipples lol) and I mustered as much courage and pulled the thread as fast as I can... yes it was exactly like pulling a bandit but multiply that by a million and not a single spot... every. single. inch.
I wanted to scream, but there were more ones that got be pulled one by one.
The ones on my shaft were relatively easy but the ones on my balls were indescribably painful. (here's something my dumbass-novice self did and probably everyone should avoid: I grabbed too much skin for each pin on my balls)
Pulling those 13 ones were by far the most pain I've ever experienced around my balls EVER.
After I was done I couldn't aim water from the shower to any of the places at all.
The pain never stopped and I had to go out hangout with my friend looking all grumpy (plus I had to drive which was painful still)
Now as I type this; the pain is fading away (1.5 hours later)
Thank you Icey for the task and the new experience.