Soft selection is a very powerful tool for modeling in 3dsmax, it allows you to select one vertex/edge/polygon and as you modify it, it affects the whole area of polys around it, it is really great.

So first go to the extended primitives to create a chamfer box, make it sure it has a good number of  width and length polys so you can handle the soft selection better, your chamfer box shall look like this:

Now convert it to an Editable Poly, Select Poly and then Check the Soft Selection Box, as it is in the right corner of the image:

Notice that i already have selected the polys i will move inwards the cushion, the soft selection falloff is set to 10, which will determine the area of polygons afected, pinch and bubble are parameters that will determine the way how gradually the soft selection will affect the area polys around your selected polygon.

Now in this image you can already see how i moved the polygons inwards the cushion and the how the soft selection made a gradual and soft movement to happen.

Now i created spheres and scaled them so that they can serve as buttons for the cushion

All you have to do now is apply a nice leather material and here is your final result:

That’s it, Good luck!