I found a couple good technic triangle designs over on brickengineer.com. For example:

How can I firmly attach a triangle to a large turntable?

Details:

• Really I only need to attach parts at the points of an equilateral triangle. These triangles are for example only; Solutions don't necessarily need to use these specific triangle designs.
• The setup should be able to rotate while bearing a small amount of weight (hence the turntable).