Today we're looking at an impressive conical roof technique by Poul-Erik Borre on Flickr. The techniques is put to great use in his 'Water Tower' MOC, which you can check out here: https://www.flickr.com/photos/dk_titan/42992802720/in/dateposted/
http://www.dk-titan.dk/legowatertower.html
The technique essentially relies on one key part - the mixel ball joint. This allows you to connect and angle each roof panel, as the ball joint can move in any direction to provide more flexible connections. From there, it's just creating a full conical shape and placing the build over the top of the tower; with no physical connections needed.