Can someone help me make a tower?

I need to make a tower for engineering. It has a minimum height of 600mm and a maximum base of 300x300mm. I have to make it out of long MDF bars,which aren't very good at supporting load, but I have found a way to make them stronger. We can also use glue, string and cardboard. The tower will be tested with a garbage bin slowly being filled with water on top of it, and we get points for how much load it can take relative to the tower's weight. Does anyone know what is the proven best design for a tower like this, like a desgn that won a championship somewhere?