Use a cutter to slice zucchini into 1/8 in (.3 cm) thick slices. Pat dry with paper towels to remove any excess moisture.
Add olive oil and toss to coat the zucchini slices thoroughly. Sprinkle lightly with salt (you need less than you may think – the slices will shrink during baking, making the flavor more intense). Toss to coat again.
Place oven safe baking racks on top of two cookies sheets, then top those with parchment paper. (The cooling rack method allows for better air circulation.) Arrange the zucchini slices in a single layer. It's fine if they touch, but make sure they don't overlap.
Bake for about 2½ hours rotating the pans halfway through. The zucchini chips are done when they are puckered and golden. If there is any moisture on the zucchini but it's already golden, pat dry with a paper towel.
Allow chips to cool in the oven with the heat off and the door propped slightly open (they will crisp up more as they cool).