Currently eye3D does not host it releases on PyPi, but uses a custom hosting.
pip does not allow installation of externally hosted packages by default anymore. This is due to many associated problems with hosts going down, HTTP being insecure, etc. This makes it more complicated for the library user to get eye3D instaleld.
I'd dare to suggest to make eye3D packages hosted on PyPi, as most mainstream Python projects do. It is very easy and you can even automate the releases: