1. How to make coloured rainbow rice:
For each colour, I used:
1 cup of rice
1/2 tsp vinegar
a gob of Wilton icing gel (you could also use several drops of liquid food colouring)
Drying the rice:
Spread each batch out on a plate or a cookie tray (I used styrofoam meat trays that had been sterilized in the dishwasher) to dry.  You can place your rice in the sun or by the fire to dry them quickly.  It’s not sunny here, but it’s too warm to have the fire going, so I’m just going to leave my trays on the dining room table over the weekend.
An easy, mess-free alternative to using ziplock bags:
Rainbow Rice!
Colouring the rice:
Pour a cup of rice into your margarine container.  Then, with a toothpick, or stir-stick or knife, whatever… (I used a plastic toothpick that I could just wipe off each time), swirl a generous dollop of colour-gel through the rice.
Drizzle your 1/2 tsp of vinegar over the rice.
 Pop the lid on your container, and shake the heck out of it.  Remove lid, and be amazed!
Supplies for dyeing vibrant rainbow rice for play:
inexpensive, long grain white rice
vinegar
food colouring or icing gels
food storage container with lid