I needed a quick and easy cover for my 20cm drain. This one is 199mm and fit nicely, could rescale to your needs. The two larger holes make it easier to remove and place as you can get your fingers in.

Print Settings

Rafts:

No

Supports:

No

Resolution:

Any, under 0.3 not really required

Infill:

I went 50% and seems strong enough, could experiment though.