n2ri wrote:these couplings are made of plyable soft plastic not what 3D printers use. they are available at HVAC supply stores even a universal kit for most sizes and lengths for under $30. need 6 inch long part for many as thats average length
i believe you are thinking of an angular deflection coupler, like a spider coupler or a love-joy. But, actually, based on how their coupler blew apart it looks like the fracture of a hard plastic not a soft plastic.
I think there's a decent chance this coupler is not needed for angular deflection reasons but rather just for assembly or something, one reason or another preventing a direct coupling (maybe even as a cheap destruction torque limiter.)
(In defense of OPs repair job.)
To OP: if it turns out you needed something softer...you can take the file you have, google "OpenSCAD molding script" and use that to generate a two part mold that you fill with a cornstarch-silicone mixture (often called "Oogloo"). It would make a flexible part. That would be intense!
[At first thought it's not super easy to mold a hollow cyclinder like that, but I'm use there is a way with more thought.]