SF Spaceship Op Shop Find

I bought this SF toy, for $10, at a Phillip Island toy op shop. There is a missing part which I might or might not have still in my car. If not I'll somehow fill in the space. The toy has three landing legs. I don't know if it is based on Star Wars.

Rather than a spaceship I am more inclined to use it as a fort.

Any ideas on modifications and paint schemes are welcome.