If using a plain kraft bag, paint it black first and let it dry completely before continuing (twenty minutes). A pre-coloured black bag skips this step.

Punch one hole on each side of the bag near the top, about 2 cm from the edge and 2 cm in from the side fold. The holes should align across from each other.

Thread one end of the pipe cleaner through the left hole from outside to inside. Bend the end over by about 3 cm inside the bag to lock it in place. Thread the other end through the right hole the same way and bend it over. The pipe cleaner forms a looping handle above the bag.

Press green foam stickers along the inside top edge of the bag, slightly overlapping the rim, so they appear to bubble up out of the cauldron. Cluster a few stickers in groups of two or three for a more irregular, bubbling look.

If you have a cotton swab and green paint, dab a few extra bubble dots on the bag front in slightly different green shades. This adds depth but is entirely optional.

Fill the bag with sweets and the handle makes it easy to carry or hang from a display.