I can’t find any good WoBs on this, and I don’t think it says anywhere on the Coppermind, but I believe it’s possible to change the size and shape, to an extent. A coppercloud is described as a bubble, as are bendalloy and cadmium. I think it is arguable, however, that a coppercloud wouldn’t function the same way as those, as a coppercloud moves around with the smoker, but a Slider or Pulser’s bubble stays in place. My personal conclusion is that, unless otherwise stated by Sanderson, it is likely that with some Savantism and practice a Smoker would be able to produce these effects. If that made sense at all. That was my thought process.