Does anyone know of a source for the black plastic clips that fix the rubbing strips? They seem to only come with a new strip rather than a separate part.

You mean the ones inside the door?

Hi Dave, no the black rubbing strip on the outside, half way up the doors which has a very fragile set of black clips which slide in a channel on the back of the strip.

As I remember the channel for the rubbing strip has pins that pop into holes in the door. These are secured on the inside with push on "spire nuts or washers"? I think they are called. I may be confusing it with another car, I have been working on a Volvo recently.

If all else fails use an industrial adhesive.

They should locate into what the parts manual refers to as cupsacs. As you say if all else fails some adhesive would do the job. I'll have an ask around about 3d printing some.

Having just checked it seems the cupsacs are available but, as you say, the bits of plastic that fit into them aren't listed separately. I know when I took my rubbing strips off when the car was going in to be resprayed some of them pulled out of the channel. Maybe they changed the material on later ones as none of mine broke, just pulled out and I had a hell of a job getting them back into the channel. If I remember right, mine appeared to be nylon.

I've got one surviving one, all the rest just shattered under the smallest pressure. I cut a small section out of one side of the channel at one end and slipped the clip out so at least have a sample to offer to a 3d printer.

can you find a counter sunk screw with a head big enough to fit in the channel on the rubbing strip, but a thread fine enough to push into the cupsac?

I doubt it, the channel is the best part of an inch wide.