You can build the base with no top. There are a lot of new Hoth sets out and new ones coming in the summer. I also used a book called "Star Wars locations", it has a layout of the Hoth Battle and a book called "The Art of Episode V". Don't want to give too much info, it may turn out better than mine. I also used A LOT of build and rebuilt again and again and again...
Quoting [Unit 33]
I've been following your progress on flickr, and it had inspired me to create a hoth scene of my own, I can't possibly match your brick supply, any tips for creating Echo Base?
Brickplumber, I would really like to know if you have LCAD or LDRAW plans for these. It would make my year if I had instructions on how to make one of your walkers. Please hit me up at email@example.com!
I like it a lot and I consider it is correctly scaled.
And having 2...that is too much for me.
How long did it take to be built?
Anyway, excellent job.
Mine is about 55-60 cms high, not much different like yours.
I feel they are mini-fig scale, but you are allowed your opinion. I got scale references from numerous books. I think they are the best thing in Lego that I have seen. I also have a scaled replica of the walker from Master Replica's and my lego ATAT matches thier scale. Master Replica's ATAT's match the exact ones used in the original movie, but then gain, you are entitled to your opinion, I just don't agree with your opinion.
Quoting hans the german
These are not mini-fig scale. Too big.