You will need:

- 100 ml of glycerin
- 200 ml of liquid dish soap
- 12 cocktail straws for the cube, and 1 more for blowing the bubbles
- Pipe cleaners (6 pieces each around 30 cm long)
- A large plastic container filled with water

Add the dish soap to the water, and stir it. Gradually pour in the glycerin, and stir again. Cut the straws and the pipe cleaners in half. Twist the pipe cleaner pieces 3 times at each tip, and bend/straighten them out as required so that they form right-angled pieces. Pass a straw piece over each piece of pipe cleaner, and twist the still-exposed ends of 4 pieces to form a cube. Lower the cube into the soapy liquid. Once it’s fully submerged, carefully remove it — there will now be soapy film stretched across each plane. If one side is bent in a certain direction, the opposite sides of the "bubble" will stick together. If you drive a straw into the center of the cube with a small round soap bubble on one end, it will soon take on a square shape as well.