rotundate
/ˌroʊtənˈdeɪt, ˈroʊtʊnˌdeɪt/Definitions
1. verb
to make or become round or spherical in shape
“The process of rotundating the balloon resulted in a perfectly round sphere.”
2. verb
to form into or shape into a sphere or ball
“The sculptor rotundated the clay into a beautiful marble sphere.”
3. noun
the act of making or becoming round or spherical in shape
“The rotundation of the balloon was impressive to watch.”