Based on the familiar offering from Alpkit I devised my own stem cell bag so I can keep food a bit handier.
It doesn’t taper like an AK version so it probably holds a bit more than their standard size. Main body is approx 20cm by 10cm diameter, 1000D nylon lined with subtle pink ripstop and the drawcord section is jade ripstop.
I bought some brass eyelets for a rucksack project so added one of these as a drainage hole in case of severe down pours, might also serve as an automatic breadcrumb distribution mechanism should I find myself lost in the woods.
Attachment via a webbing ladder around the top of the main body and a webbing loop across the base.

Capacity is easily a 750ml bottle, or err, 6 lemons (didn’t have much else to hand and it was pancake day...)

Good effort. I started out making stem cells and was surprised as to how easy and quick they are to make once you've got the pattern and the steps in the right order.

I like the drainage hole. For some reason I immediately thought of the Great Escape and you cycling round depositing the soil from Tom, Dick and Harry. Not that Lockdown is making me think about digging my way out the house.

On a stemcell version I made I did a rolltop closure to protect my electronic stuff a bit more from the elements, albeit that they were also in drybags/ziplock inside it.