Google - Rocket Cake Designs

How big do you want it to be?
 
Start with 8 inch layers going up to 3 inch layers top with the waffle cone.  If it has to be all edible use long pretzel sticks as dowels otherwise use dowels.

Freeze the cakes before final stacking and frosting.  Find a stiff ready made frosting and use it as glue in between the layers. 

Hope it works out for you.