All you need is citrus fruit; oranges, apples, pears, limes, etc. and whole cloves. I was at the grocery store the other day and picked up some oranges and apples. Since I was buying them for decoration I found some that were wrapped with a shorter shelf life. I got 2 bags of 4 fruits for $0.89 a piece.
You could do this sitting on the couch but use a plate or bowl so you don't get the fruit juices or the clove pieces anywhere.
Take a clove and pierce the skin of the fruit and push all the way in. You can use a tiny screwdriver or a sharp nail or any type of prodding tool to start your holes if you want to. The cloves might make your fingers hurt so for children you probably want to start the holes to make it easier for them. Just continue adding cloves until you have the design you want.
You can use masking tape to cover parts of the fruit to make an outline of your design or you can first tape down ribbon and put cloves in the fruit through the ribbon to add some color. My son and I simply did ours freehand and we enjoyed it.