Recently I bought a Field View Mill to convert to a lighthouse (at that time there wasn't a Sylvanian lighthouse).
1. First step- take the top off the mill
There is a lovely groove which makes the conversion easier.
2. Second step, cut a circle the size of the base of the blue observatory.
3. Cut a straight piece approximately 11cm wide & long enough to wrap around the circle.
4. Glue together & place on top story. Make sure it sits snuggly inside the groove.
It's starting to take shape.
5. Cut the style of lighthouse lantern that you want.