Here is an easy way to construct tubular fuselage sections from
inexpensive Dollar Tree (Readi-Board) foamboard, hot glue, and packing
tape. They can be in diameters from 1 1/2" to 5", in square or
rectangular cross sections, straight or tapered. They are logically
manufactured in 30" long sections but are easily joined.
The actual "How-To" part starts at 3:20 in the video. Also see links in this video to associated videos about different method of making the lap joint for the fuselage tube with Gorilla Glue (slower but easier and more precise in outcome) as well as variations on the tube design (tapers, rectangular cross sections, etc.).This fuselage tube makes a great companion to the Armin Wing airfoil design