I came across the above image from a post that an Art teacher friend of mine posted yesterday. I currently use a similar system, but they clog all of the time and they have a tendency to explode as a result (maybe you have seen the aftermath of this on students' clothing at some point over the last year).
Although I love putting ketchup on almost everything, there is no way I will be able to go through enough to get the bottles needed to implement this in my classroom for the Fall. If possible, please save and clean empty bottles so that I can upgrade to this system and save your children from exploding paint bottles. I would be in need of 10 bottles total. If you are able to contribute to the cause, please respond to this post. I can start accepting bottles as soon as you are ready to send them my way.
Thank you for your help and support!
BCWMS Visual Arts Teacher