Based on the 1000-rep challenge. (If you aren't familiar with this, it's simple. Do 1000 snatches without putting down the kettlebell. You can change hands as often as you like. Rest position is the lockout at the top of the snatch)
For the proposed version, I want to do 1000 reps with the same hand. My suggestion is a 12kg kettlebell. I thought maybe even allow a racked rest position as well as the overhead lockout. I did test if it was even vaguely possible, using the LastManStanding workout trial run