2-part thing to neaten a hole through a hollow wall?

That's a very big hole. I hope you meant mm.

If you make a suitable hole right through the wall you don't need a tube in two halves; just use one piece cut to the right length. A short piece of plastic drainpipe would work. Or the duct meant for use when people put extractor fans through walls.

When I needed to do that, I used a bit of kitchen extractor ducting through the wall, with a couple of wall plates from the same range to finish the ends.

If you did not want to push the plugs through, could you not make do with a much smaller hole? Use an extension lead, and plug into that?

Good gravy, yes.

Hmm, extractor fan parts might be good.

I did exactly this with a bit of 40mm wastepipe, same sized holesaw and a tube of caulk. Takes IEC/kettle connectors quite happily. If the ends had been visible I'd have stuck a brush plate over each (

Yes but its the way the plaster splits and crumbes at the edges. There used to be a gadget that shop fitters and those office partition builders used to use like this, but like others, I have no idea what it was called, but as most interior walls of this sort were very thin, I'd imagine itt would be too short. Brian

Would it not be much neater to fit a socket in the wall?

NT

On further consideration, I think I'm only going to put one thing (the WAP) there, so I just need a small hole to pass a network cable and the small DC plug coming from the wall wart through the wall. I might use one of those "brush" faceplates, probably with a back box, a short piece of flexible conduit, & some kind of caulk around the conduit on the other side (which will be inside a wardrobe).