I use the 'milk trays'. They're basically like ice cube makers but longer in shapes. And is abt 30ml per stick. The local ABA ladies put me onto them and said to put some sticker on the top and use whiteboard marker to write the date on. When I send it to cc I either put it in the bottle as it is and it's defrosted in the bottle/fridge. Or I just put the sticks in zip lock bags.