The sketch is done in gouache and stands about 5" high. The sculpture made a great impression on me when we were in Rome a couple of years ago. It stands alone in the square before the church in which Saint Catherine's body is interred, supporting an Egyptian obelisk capped with an ornamental cross. It strikes me as quintessentially Catholic, ever ancient and ever new.
As a bonus, here is an ant that I recently drew.
The unfortunate ant had found her way into my kitchen, which was for her a trackless desert.