Ozone trays are easy to make. First thing you need to do, is find out what type of attachment is required to attach the ozone hose. The ones used here, are compatible with "lurlock " connectors.
you need a good quality impression with nice full borders. I've used base plate wax, softened and adapted over the teeth as a spacer. Unlike Mark's suggestion to use pulldown material, we've been using Siltex from Ivoclar to form the trays. An average sized arch, will require two scoops of base material. On the model, mark the location of the cuspids, as this is where the hose connectors will be located. After the Siltex material has been mixed, adapted to the arch making sure to bring the material a couple millimeters down onto the gingiva. The objective is to make a tight seal here. Take 2 of the connectors, and position them so they are angled at approximately 45° angle over the cuspids. Pinch the material securely around them so you'll have a good seal. After the Siltex has set, remove from model and remove the base plate wax, and using the end of a HP Burr to remove any blockage.