It's a 3" body tube with 6" styrofoam balls cored and slide into place. The long tanks are 29mm tubes with plastic ball halves on the ends. Legs are 1/4 birch ply. The nosecone is another clear plastic ball half. It's 40 inches tall and weighs 60 ounces with a 70" parachute and blanket. I have a similar rocket that has a CD of 2.0. So that's what I put into Thrustcurve. That tells me it will fly to 659' on a I-140 with a 4 second delay. I'll test fly it in private before I take it to a club launch. CG is at the base of the upper ball. I believe the CP is at the top of the lower ball.