You can make the model of eye using clay..if you want it bigger in size use plaster of paris (before using read the guidelines and be careful ) to make it  colorful use paint etc.

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To make a model of an eye 
The materials required are:
1. A big plastic ball
2. A piece of pvc pipe
3. Circular piece of tracing paper,acrylic sheet,convex lens of focal length 10 cm.

stick butter paper on acrylic sheet (this will make retina for the image).
apply glue on the border of the pipe and stick the acrylic butter paper disc on it.
then cut the plastic ball into two halves and then make a big hole in centre of one and a small hole on the other half.
then apply glue on the border of the small hole and stick convex lens on the small hole
make sure that the larger hole should be fit to the retina pipe and then slide the retina pipe into the big hole.
then close the ball halves and tape it or stick it in any way.
we finished the model here .

slide the retina pipe in and out to get sharper and perfect image .
and at seeing through the retina pipe we would see the inverted image 
it is how we see all the things 

thanks may it help you as its a cheap and useful way .

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