Place 2 PVC tubes measuring 50cm/20in long by 5cm/2in diameter on a flat surface, parallel to each other, 10cm/4in apart; secure them to the work surface with tape. Cover the tubes with parchment paper.
Temper the milk chocolate and then stir in the cocoa powder. Place inside a piping bag fitted with a #2 plain piping tip.
Pipe irregular strands onto the PVC tube setup, going from one PVC tube across to the other; try to obtain sets of 3 to 4 strands of the chocolate-cocoa mixture. Make at least 10 sets (1 per dessert order).
Let them harden at room temperature.
Once they have hardened, dampen a cloth towel with warm water and rub the surface of each piece to smooth it out by rubbing it with the towel. Dip the cloth in warm water and wring it out between rubbing each piece of décor so that the warm water can help with smoothing out the surface of the chocolate.
Once all of the pieces are smooth, brush them with edible gold luster dust, taking care to remove any excess.
Reserve in a cool, dry area, preferably enclosed. Discard after 6 months.