Have to say i LOVE that sound dave gilmour does as rick is playing the keyboards, as it all gets to a progressivly larger sound.

I just have no idea what exactly he does. I dont have a slide (yet) but i had tried a couple of things (such as bottlenecks) just to see if i can recreate the sound dave makes, and I am just not able to get the sound...

Does anyone have any idea how to recreate this sound?