Simplest 5_8mm coupler you can made.
https://jide-projects.obs.myhuaweicloud.com/xV95qAcRsEJfY/
Model Inspector
Size and Count
Matcap
Wireframe
Vertex Normals
UV Checker
Base Color
Metalness
Roughness
Clipping
Simplest 5_8mm coupler you can made.