Step 2: Make Templates For Structure
Other materials (plastics, wood) can also be used. If you don't want to go to the expense of waterjetting, you can use a jig saw or band saw to make your parts.
My templates were made to accomodate 6 plastic bottles that are about a liter each. Your bottles may be different, so make your parts according to how many bottles/size of them.
You can see my finished template for the base, bottle support, and bottle holders. Also there is the valve support and the compressed air tank supports.