Pour the tempered chocolate onto an acetate strip cut to 17.5cm / 7in by 30cm / 12in and spread to a thin layer. Pick the acetate up and move it away from where it was to get a clean border.
When the chocolate is partially set, use a ruler and the back of a paring knife to cut long, thin triangles, from the top to the bottom of the acetate. They should be 1.75cm / .5 in wide at the base. Work quickly, because once the chocolate sets too much it will crack when it is cut.
Place the acetate on a PVC tube 6.25cm / 2.5in by 30cm / 12 in, with the chocolate facing the tube. Tape the acetate to the tube so that it takes the shape of the tube exactly to form long, thin, curved triangles.
Let the chocolate set. Once it is set, leave it on the acetate until it is needed and then remove it from the PVC tube.