In a saucepan over low heat, melt the cocoa butter until the temperature reaches 86°F (30°C).
Using a small paintbrush, paint the cocoa butter into attractive designs over the inside of the molds.
Let set while you temper the chocolate.
Transfer the chocolate to the pastry bag and pipe it into the molds filling them completely.
Invert the molds to allow excess chocolate to drain out, saving the excess for sealing the bonbons.
Using the scraper, scrape the tops of the molds so the edges are clean.
Stand the molds upright and let the chocolate set for at least 20 minutes at room temperature.
Wearing thick gloves to protect your hands from thorns, peel the prickly pears and pass them through the juicer.
Measure out 4 tsp (20 ml) of the juice and set aside.
Measure out 80 ml of the juice and place in a saucepan with the sugar.
Heat until the sugar dissolves and the temperature of the syrup reaches 265°F (130°C).
Remove from the heat, add the tequila and the 4 tsp (20 ml) juice to stop the cooking.
Carefully pour the syrup back and forth between two bowls to cool it down. Let cool to about 68°F (20°C) before using.
Transfer the prickly pear filling (at 68°F (20°C) to the piston funnel and fill the chocolate shells two-thirds full.
Re-temper the chocolate leftover from making the shells, if necessary.
Using an offset spatula, divide the chocolate between the acetate sheets, spreading it in a thin layer.
Invert the sheets over the chocolate molds to seal the bonbons, running the scraper over the acetate sheets to smooth out the chocolate.
Let set for about 20 minutes before removing the sheets and carefully turning the molds upside down to remove the bonbons.