I use these: https://www.amazon.com/Rubbermaid-Refill-Bottle-Assorted-1787306/dp/B004RLNF00/ref=sr_1_1?dchild=1&keywords=rubbermaid+20+oz+bottle&qid=1597165977&sr=8-1

They are the perfect size for one portion, are small, dishwasher safe, and cheap.