Well, long ago I read up on it a bit, and the theory and simple plans are not that hard to understand, and even building one, the mechanics don't look so difficult. The hard part would be getting the last several stages of fuel. Especially that last one. I don't think I'd want to mess with that stuff no matter how much they paid me. Their ain't no suit thick enough for that

But I have to read up on that story. Could have been another Swede, you've really piqued my interest now!