Thinly slice the cucumbers in 1/8 inch slices. In a single layer, line cucumbers on a paper towel. Place another paper towel on top and press into the cucumber slices to draw out excess moisture. Repeat this process twice if necessary. The dryer they are, the crisper they will get as they bake. Place dry cucumber slices in a large mixing bowl. Preheat oven to 200° In a small mixing bowl combine dill, onion powder, garlic powder and apple cider vinegar. Pour herb vinegar mixture on top of cucumber slices. (It will be a thick mixture) Toss cucumbers until each one is saturated with the herb mixture. Line two large baking sheets with parchment paper. Line the cucumber slices on the parchment paper in a single layer. Sprinkle with a little sea salt. Bake for 3 hours (longer if necessary), rotating trays half way through. Turn oven off and allow the trays to cool in the oven. This will help them get even crispier.