When i was planning on building our house there was that many sites on the computer that you could do a 3d design and look around each room and change things too.
I am sure if you have the time to look something may turn up.
When you see these house program on tv today they do what i did years ago but better.
Like Simon has mentioned what about a 3D printer , may be in sections then place it all together.
Would you like the members on here to save there inner loo rolls and cereal boxes , I would mention Emma's shoe box collection but you could build a city with all those