I started by making a plaster pattern in a plastic mould. I painted the plaster cast yellow to hang it on the bathroom wall (decorative and could be used as pattern again). After the paint was dry I varnished the plaster cast so it will be easy to remove it out of the petrobond sand.
To get the plaster pattern out of the mould I used 2 screws on the back, The mould was perfect.
Then I made the sprue and riser on the back of the sun, I predicted there will be some aluminum shrinkage because the amount of molten aluminum used in this casting.
The pouring part was the easy part I was all most short with the molten aluminum but it was just enough to fill the sprue and riser extension half way up.
The sun casting turned out very well, some shrinkage on the back because the lack of aluminum to feed the mould. You can see in the image that the sprue and riser extension did their part. The only thing left to do was to cut off the sprue and riser with a grinder make two holes for screws and hang it on the wall.