I have considered doing this myself before. If you want something more weather tight I have seen where they use logs like in a wood pile like that with mortor between them. I can't remember the official term for that sort of construction. Whe I built my tower blind - Ibuild it ina modular fashion and then takeit apart and to the field. While it is at the house however it turns into a play house for my girls. My boy and his friends like to use my tower blinds for paint ball - they have discovered the tactical advantage of height! Looks like a rainbow crapped all over it at times!!!