Design an icon for my small software

I have a small software tool for calculating something in the oil & gas industry. It is based on MS Excel. It has something to do with sand in oil / gas pipeline. The software tool's name can be shorten to four letters which we want to put in the icon. What we want you to do is to design this icon. The budget for this project is $30. You need to show me your design in your bid. I will not choose any bid without demo. In your demo, use "SRRS" or whatever four capital letters you want as the software's short name. Later when I choose your design, I will tell you the true name (4 letters) of this software.