Colours pasta, rice and fingers black as the ace of spades. You need one sachet per 50g of DRY rice. Instructions included.
The SERIOUS EATS website wrote up cuttlefish ink (at any rate, squid ink) here.
This Australian site has some good ideas too.
And if you can create one of these, we'll stand to attention.
Our single shot sachets are priced to go because we have a lot to shift before their expiry date of August 2016.