It took a single click I wasn't even farming the rack. And funny enough, she dropped another in nightmare act 2 from a monster a day or two later.
But in all seriousness, I think racking is surely the way to go if you're searching for sanders helm or blinkbats specifically. Sanders helm has qlvl 20 and racks drop items of ilvl=alvl-1. So normal LK (alvl 22) should be able to drop it. And sets should be 1 in 125 as i understand it (mf doesn't matter). So if you can reroll maps in normal LK till you get a stable cap armor rack, it should take no time at all. Or no more than a couple hundred runs anyways.
Haha no problem. Racks in diablo 2 are weird and you can find a few other threads on them. Note that 1.07 racks are much more stable than those in modern versions. But in general, yes you can roll a map with an armor rack that drops only caps. If you approach the rack from the same direction each time (or telekinesis it from same spot if you are sorc), and there are no monsters around it, a rack usually drops the same item most of the time. So I would say your goal is to find a rack in LK that drops a cap >50% of the time. It should only be a matter of a handful of hours after that. So if drops caps 50% of the time from your rack, and 1 in 125 are set, and 1 in 2 sets are sanders rather than infernal, then that's 500 average runs, which shouldn't take too long if you just tele to the rack and s/e. So not trivial though. Would take a few hours. ~3hrs if 20s runs.
And its probably already clear, but just to reiterate. LK is probably the best spot for this just because there's a a waypoint and tons of racks, but if you stumble on a stable cap rack elsewhere, definitely check to make sure alvl >= 21. Would suck to find one in tower lvl 1 and wonder why it only drops infernal's