The Jeltsch Laboratory has sponsored the giant soap bubbles for the Flora daycare center activities at the Arabia street festival.
The recipe is available from here: https://jeltsch.org/soapbubbles/#soap_bubbles. Unfortunately, the specific type of wallpaper glue I used in the recipe (Kiilto jauheliisteri) is not anymore easily available and I need to test another brand for its suitability...