Washer fluid bottle is obviously meant to store a water methanol mixture in it for some time, has anyone actually just tapped one to use for a meth tank itself? Thought that would be interesting, not sure how it would be secured though 
Maybe tap the cap itself for the drain fitting, mount it upside down, and just swap bottles when low lol

Maybe tap the cap itself for the drain fitting, mount it upside down, and just swap bottles when low lol