what is a good recipe for a practice icing?something i could possible reuse?

I use the Wilton recipe for practise. I know it is listed on their website. I used this threw my 12 week course and it seemed to be okay to leave on the counter when I used water. If you use milk you need to put it in the fridge.
Shannie

If I'm not going to eat it, I just use a cup of crisco, 2 tbsp of water and a pound of powdered sugar. Mix water and crisco on medium until smooth, the mix on low until everything is combined and smooth. Add more water (1 tbsp at a time) until you reach the desired consistency...tastes horrible but it works