Remove any broken seeds or seeds poking out of the cores. Combine apple scraps, water and sugar in a large, wide-mouth glass or ceramic vessel and stir. Cover with a thin cloth.
Over the next several days, stir your fermentation several times a day when you think of it. After a fews days, your concoction should start to bubble and begin to smell slightly alcoholic.
Once the ferment starts bubbling, stir it once a day.
Continue to stir daily. Fermentation times vary, but your vinegar will likely start to taste sour after about one more week. At this point you may strain the fruit out and compost the spent scraps.
Bottle your vinegar if you detect no carbonation. Although you may see no evidence of bubbling, and believe the fermentation has ended, this may not be the case. To avoid messes—or worse, explosions—burp your stored vinegar occasionally if you see any bubbles whatsoever. This vinegar will keep indefinitely.