1. In a small pot, stir water, sugar and cornstarch. Whisk over low heat for 5 minutes until mixture is thick and clear. Note: We stirred over low heat for over 10 minutes with no change so I turned up the heat and brought the mixture just under a boiling point. Then it thickened really nice.
2. Stir in corn syrup. Pour (or scoop) into small containers with lids.
3. Add a few drops of food coloring to each and shake until color is well mixed.
Ours thickened up a lot so I stirred in the food coloring instead of shaking.
Update: This fingerpaint does not do well stored long term- over a few days. Ours grew black mold- yucky!