Lois,
I found this on the web. It tells you how to make your own Castor Sugar. Don't you just love the internet?
Castor sugar may not be easy to track down, but it is easy to make. In fact, it's really nothing more than granulated sugar that has been ground to a super-fine consistency. Here's how to make your own castor sugar in seconds:
Ingredients:
Granulated sugar
Preparation:
1. Place granulated sugar in a food processor or blender.
2. Pulse until it reaches a super-fine, but not powdery consistency.
3. Allow the sugar to settle for a few minutes. Then, use in place of the castor sugar called for in your recipe.
Tips:
1. Sugar may etch your blender pitcher, particularly if it's made of plastic. If this is a concern, use a coffee grinder or spice grinder instead.