Pour the sand or dried rice into the base of the bag. This keeps the bag upright and weighted. Three tablespoons is enough to stabilise most lunch bags.

Draw a spider-web pattern on the front panel of the bag lightly in pencil. A web radiates from one corner with five or six concentric arcs crossing the spokes. Keep it simple.

An adult uses the craft knife on a cutting mat to cut away the spaces between the web lines, leaving only the web frame in place on the bag. Take your time: the cuts are small and fiddly, and tearing the bag at a join means starting again with a fresh one. Cut toward you and replace the blade if it starts dragging.

Cut a square of white tissue paper slightly larger than the cut-out area and glue it to the inside of the bag front, covering all the cut-out spaces. Smooth it flat so there are no wrinkles over the openings. When lit, the tissue glows and the kraft web reads as a dark silhouette against it.

Cut a small spider from black card, about 3 cm across with eight legs, and glue it somewhere on the tissue patch. Even a rough spider shape reads clearly when backlit.

Drop the battery tea light into the base of the bag among the sand. Switch it on before placing the lantern, as the inside is hard to reach once the bag is positioned.