Is there a proper name for this particular cover/plug/pin/bung?

[Halcyon]

A bit of an odd one... I'm after a flexible/compliant rubber or silicone "plug" with a flat head that I can just push-fit into small holes in both timber and metal, to essentially cover and disguise the hole. Similar to the little end-pins you get with some ESD tubes to keep IC's from falling out the ends. I don't know if there is a proper name for these or if anyone can suggest a product they've used in the past.

The holes are approximately 3.5 to 4.0mm in diameter.

[44kgk1lkf6u]

Searching for ribbed plug yielded some results.

[notsob]

Try google for "blind hole plug"

[abeyer]

Searching for ribbed plug yielded some results.

yeah... for certain types of holes that need plugging.

[shabaz]

I believe the technical term (as Beavis & Butthead would also describe it) is, as you say, a bung.

There are silicone bungs (photo below), or, if you don't want that level of softness, perhaps plastic blind rivets (or variants such as the ones in the photo below) might suit your needs. Those plastic rivets are really handy for all sorts of purposes, e.g. keep two sheets joined together, but they could also just be used as a plug.

This site has a lot of the plastic options.

For full flushness, there are rubber tapered plugs (photo of those below too).

[SeanB]

Easiest is a tube of acrylic or silicone sealer, and wipe over the hole to leave a blob in the hole, and wipe after with a damp cloth. Fast, cheap, and works well.

[Halcyon]

Easiest is a tube of acrylic or silicone sealer, and wipe over the hole to leave a blob in the hole, and wipe after with a damp cloth. Fast, cheap, and works well.

In this instance I want it to be removable.

I ended up finding something (which I hope works) listed under "Snap in locking hole plugs, rubber panel seal cover flush type panel round for kitchen rubber bulkheads waterproof sealing plugs" (read in Big Clive's voice).

[EPAIII]

Rubber corks?

[armandine2]

grommet gets used here

https://www.reevite.co.uk/grommets/blind

[T3sl4co1l]

Brings to mind such as these,
https://www.mcmaster.com/products/hole-covers/protective-plugs~/
of course YMMV, you'll probably want to find your local equivalent as McMaster is fairly US-specific IIRC, but as a list of examples, that's fine.

Tim