I have a shower with tile walls and a plastic floor and a drain in the center. I have never been able to fit the plastic drain cover onto the rest of the drain. The drain itself has a black rubber cylinder lining it on the inside that is about 1/2 inches thick all around, leaving about 2" diameter for the water to drain.

This black rubber "pipe" goes down as far as I can see and prevents the plastic drain cover from fitting in. I'm not sure what I am supposed to do to end up with a finished drain that has a secure cover that's flush with the rest of the shower floor.

Why not purchase a snap in shower strainer, (see image). Good luck, Tom

Yeah... I have come close to doing that, I would have to find one that fits the 2" hole yet has a flat top that extends to the 4 1/2" that would be needed to cover the indention in the floor of the shower.

Are you saying the installer never installed a strainer? He just left you with a open drain hole? How old's the job? Tom