Phone cases printed from regular plastic aren't that great in my experience, you really need to use plastic with some flex (like TPU). The Ender 3 can print fle

Phone cases printed from regular plastic aren't that great in my experience, you really need to use plastic with some flex (like TPU). The Ender 3 can print flexible filaments to some degree, but it's not very good at it without some significant modifications to constrain the filament path.