I use a plastic strainer that fits nicely into a plastic jug.
I place a piece of muslin inside the strainer and then pour in a whole container of my favourite five:am plain yoghurt.
It then needs something on the top to weigh it down. This pushed all of the liquid out. The liquid is full of pro-biotic so good to put into food or a drink.
This one I left in the fridge for a few days but usually 24 hours is enough.
The strainer I use gives it a great pattern but I don't have a dish big enough to keep it in like this so I've squashed it into the glass container below.