Light weight tower design?

i need to design a light weight tower. Please advise for how to build one or where to find helpful information. the tower should be less then 13 grams, hold 15 kilograms and be about 50.0 cm Minimum. Above 15.0 cm it should fit into a 8 cm (diameter) round hole. It should span 20.0 cm square opening and be only made of wood and commercially available glue.