Here is a tower technique that uses no special parts other than a bunch of Travis bricks. A complete tower or circle would have 20 sides. As seen here, it is a bit unstable, but that could be solved with further reinforcement.
Next we can lay down a foundation of plates for the middle. Then add a turntable piece which will allow you to add another plate at any angle to strengthen the tower. This technique can be used to add strength to the tower when ever you feel it needs it.