Butter is used to glue a piece of pasta to each disk. When the edges of the disks are immersed in hot water, the butter on the diamond melts more rapidly, releasing the piece of pasta.
When memory metal is bent, it deforms. When placed into hot water, the metal "remembers" its original shape.
A metal bobby pin is heated until red hot, then allowed to cool slowly; this process is called annealing. The annealed bobby pin is very flexible.
The tempering process, which involves heating a hardened bobby pin then cooling slowly, transforms the brittle metal into springy metal.
An annealed bobby pin is heated, then cooled quickly; this process is called hardening. The hardened bobby pin is brittle.