Source: 2025 Q4 Beartracks, George Huntington
DUPLICATING FITTED TUBE ENDS: For example, if you have fit a tube for one side of the fuselage, and want to make a second tube for the other side:
-Stick a small piece of 2-sided tape place between the two tubes at each end, then wrap masking tape around both tubes near the ends (leave a space for marking). This helps to hold the 2 pieces of tubing secure without either one turning.


-Next take a new box cutter blade and using the back side, draw it across the sides of the tube. This makes a perfect straight line down the tubes, as you just remove the manufacturing scale. Be careful not to press too hard, as you only want a nice fine line. A small fine file works good for this step also.
-While the two tubes are taped together, the other side can be marked also, giving you a nice center line on both sides. This can be useful in drilling a straight hole, by drilling from each side.
-Take a piece of paper and wrap it around both ends of the fitted tube, slightly overhanging the coped ends. Tape the paper to itself, but not too tight as you’ll want to slide it off of one tube and onto the new one. You can also use a rubber band to hold the paper in place while still being able to move it around.
– Use a half round file on each end of the tube to remove the excess paper from the fitted ends. The file is cutting the paper where it is rubbing the paper between the tube end and the file. When done, the paper will have the exact shape of the fitted tube.
-Next take a sharp pencil and mark the other end of the paper, corresponding to the center line that you scribed on the tube. Measure and record the distance between the 2 pieces of paper, or the total length of the tube.
–Slide each paper off of that first tube, and onto the next tube you want to cut to fit. Set the length and align the pencil marks with the scribe mark along the length of the tube. Using a felt marker, trace the paper’s outline on the ends of the tube. Now the tube can be trimmed to make a duplicate tube.
If you want to make the same tube but mirror it for the opposite side of the fuselage, untape the paper templates and roll them up opposite way around the tube, making sure you can still see the pencil marks for the centerline. Install them as above, mark and cut the tube. Now you have made a left and right tube.