wood joints 
This a education app introducing the technique of making a wood product, the different structures of traditional wood joints, there are over 20 different wood joints model inside the app, which would show a lot of details about the structure, also it could tell a lot of tool’s history and some background histories.
https://itunes.apple.com/us/app/wood-joints/id837964581?mt=8
tengami 
https://itunes.apple.com/us/app/tengami/id794960248?mt=8