Tupperware's freezer range is state of the art. They stay flexible at freezer temperatures, and they are designed for fast and efficient freezing with maximum air flow.
And don't forget to make some ice.
*Tupperware catalogue: Spring-Summer 2020
D20 Freezer Mates Small Low 450ml (4)
D21 Freezer Mates Medium Low 1.1L
D22 Freezer Mates Small High 1.1L (2)
D23 Freezer Mates starter set (5 pieces)
D24 Freezer Mates Large Low 2.25L
D25 Freezer Mates Medium High 2.5L
D26 Freezer Mates Mini 170ml (2)
D52 Cool Cubes