"Chance operations" refers to making decisions or choices randomly, without any particular reason or process. It is like flipping a coin or drawing straws to decide something, rather than using logical thinking or planning. Full definition
Generally, the concept of chance operations as employed by Merce Cunningham and John Cage has been a major influence, as has the exploration of the «open work» in the writing of Umberto Eco, or for example in Lygia Clark's series Bichos. (burnaway.org)
Often the foam serves as a means to undermine the function of another object and sometimes the foam is allowed through chance operations to assume its own unpredictable and often absurdly ridiculous shape mimicking some type of organic form. (artefuse.com)