Nikon FM3A accessories needed

Hi guys, I fear the lack of motor coupling cap on the bottom of the FM3A I own may let the dust get into the camera. Is this a real possibility ? I had a look for a replacement, but no luck (it may be that I haven't search in the right places). Also, I wear glasses and I have accidentally touched (at times) the viewfinder's ring. I guess a rubber eyecup (the round one, not the oval) may prevent that.

Anyone knows what exactly I need, in terms of codes or proper names, please? Alternatively, pointing me in the right direction would not go amiss. Thanking all in advance,

Regards,
JT

The FM3a is using MD11/12 as the other cameras in the FMx/FEx range, right?
Then no base cover is needed - and don't exist to the best of my knowlege.

The rubber ring at the ocular is the standard for FMx/FEx/FA cameras - available from Nikon - but why do you need another just because you touched the ring?
If the camera has lost the rubber ring (as many have) then just contact your local Nikon rep and ask for a FM/FE/FA rubber ring:
The product at Amazon linked above is over-priced and may be cheaper if contacting Nikon directly. I normally buy a handfull when I visit Japan every two or three years - it cost around €10 in Japan.

There is no rubber ring onto the viewfinder, only the metallic knurled one, unfortunately .

Thank you, Nitroplait, appreciated. I will follow the info provided.

Best,

I have a rubber ring on my FM3a and my FE Viewfinders. Both take the same part. They are always in stock at B&H Photo.

Thank you, Kivis, appreciated. Just to be clear on what I am looking for here, this is the eye piece I seek. I believe this is not good for FM3A, but I know there a similar one (DK-3) for this camera model. Any idea where to to get it, or the proper code for it? Thank you for your kind input!