To be honest, I'd tell that sister 'No, do it yourself!', because nobody would get me to do a 3-inch Ohio Star, not matter what method.
But if you look on this as a wonderful challenge that you simply can't pass on, and you can't find a pattern, you can always take a pattern for a larger star and reduce it on a photocopier, or on the computer in a programme like 'photoshop'.
Lorchen (who'll never do anything that could be described as miniature - life's too short
)