Put 3 Tablespoons cider vinegar in a large bowl, and add a teaspoon of sea salt. Slice the zucchini thinly, about ⅛ inch thick. Take out the big tough seeds. This may mean you have to slice your squash lengthwise, to remove the seeds, yielding half circles instead of circles. That’s fine. 

Put the sliced zucchini in the bowl and use your hands to mix the slices well with the vinegar and salt at the bottom of the bowl. You can let this soak for a half hour.

Now spread your slices out on the food dryer shelves, making sure they don’t overlap or rest against each other. You want the warm air to circulate around them freely. Turn on the heat to 105-115F (40-46C). I check them every few hours, turning them over now and then. When they seem pretty crisp, they are done. I say “pretty” crisp because the vinegar makes them a tad more leathery than a potato chip. If they are quite dry, store your chips in a jar or ziplock, away from light.