I wanted to use a Nalgene bottle on my Sodastream.

I took the Nalgene lid from CaseCrafts, and combined it with the adapter from CreativeTools and tried it.

NOTE- THIS IS NOT WORKABLE AT THE MOMENT- printing with FDM leaves miniscule gaps throughout the print. When I tried to carbonate water, the air just leaked out through the whole print. I think this will be possible with a resin printer, or perhaps sealing the lid with some type of (food safe) glue.