i sew (on occasion
), and to achieve that look with fabric, you take a tube of fabric and add a gatering thread to the top, pull the thread to gather the top edge until it is the desired size, then you would sew the gathered edge to the structured top, creating a flowing, gently gathered bottom. the wider your tube, the more ruffly your end product. soooo, (tmi??) i would think the same principle would work with knitting. and i agree, a lighter wieght yarn with a soft drape would be best. i would think the best way to do this in the round or in one piece would be to do the increases as quick as possible, otherwise you would just end up with an a-line shape, as opposed to actual ruffling.