Need Recommendations for Reusable Bottles Similar to RTD

I'm currently drinking three Huel Black shakes from powder each day. I prepare them in the evening and store them in the fridge overnight. I have three Huel shakers, but they take up too much space in my bag during the day.

I really like the compact size of the RTD bottles, but I can’t justify paying £3.40 per portion when the powder costs half that.

Ideally, I’d like to be able to mix the powder in a shaker and then transfer it to a bottle similar to the RTD ones. I know I could just reuse the RTD bottles, but the plastic doesn’t seem very durable and would probably degrade after a few washes.

Does anyone have any bottle recommendations that are similar in size and shape to the RTD bottles?

4o