A plastic measuring jug or a cup will do the trick.
Probably overkill here, but....
for the DIY small scale - I've found re-using one of the supermarket plastic soup pots quite useful. (Not the tiny ones that pasta sauces typically come in!)
Cleaned out etc and filled with water, then work out where 4:1, 3:1, 5:1 is and marked a line where PVA should come to (allowing for some mixing space)
Then you can put the lid back on & give it a shake. Found it easier than mixing in a tray etc.
They're always disposable as well when they get a bit mucky.