If you want to really go nuts with this, you could use different grains or rice (vermicelli, couscous, really anything!) If you were doing different grains, it would look great to just leave them naturally colored. You could also paint over the top to give it a different look.
Bag of white rice
Construction paper or tag board
1. Pour the rice into plastic bags and drip several drops of food coloring onto the rice. Close the bag and shake (Be a little careful or you’ll be sweeping up pounds of blue rice–like me.) If you didn’t use a ton coloring, you can just leave the bag out and open for a while. If your rice is really wet, you’ll want to pour it onto paper towels to dry out.
2. Sketch out your design onto the cardboard. Keep it fairly simple with larger spaces for best results.
3. Spread glue over a section and cover with rice. It is easiest if you start with the smaller design sections, then fill in the background color. (Actually, it looks great without a background too. The design stands out really well this way.) You can pour the rice onto the glue, then dump the excess rice off onto a sheet of construction and then bend the paper into a funnel and pour it back into the bag. You can also apply smaller amounts then press the rice into the picture. (This is the method I liked best.)
4. Repeat until all of your picture is filled in with colored rice.
5. You may want to dot a little extra glue over the top of any areas that don’t look well glued. It will seep into the rice and dry clear.
6. If you used tag board, cardstock, or cardboard, you can keep it from curling by laying a book (preferably with a laminated or glossy cover.) Then top with something heavy (such as more books stacked on top). Let it dry like this overnight.