Table 1: List of materials used in our model. Instead of gel wax, gelatine can be used to reduce costs. Any kind of plastic container with a square form is suitable as well.

MaterialRetailer (for our model)Cost (euro)

Container made of PVC-planks, thickness 0.3 mmModulor, 10969 Berlin, Art.Nr: 1329309.50

Gel waxMixed Store, 74532 Ilshofen23.99

Gel (4 l)Sonosid 1 L, Asid Bonz GmbH, 71083 Herrenberg, PZN 53623113.55 (x4)

Balloon about 30 cmBasis Balloons, Luftballonwelt, 21436 Marschacht, Art.Nr: 902300.15

Red inkWinsor & Newton INK “Deep Red”, England, London HA35RH4.69

Celluloid ballElite 1*, DONIC Schildkröt, D-82515 Wolfratshausen0.49

Silicon skin/Thera-BandSchmidt Sports PHYSIO TAPE, 42699 Solingen, Art.Nr. 1112027.59