i have a simple way of sketchuping this sofa
first draw it straight boxed for the sitting part making the base and coussions as boxes then round the corners of the top and bottom faces of the cousions then in order to make them bombe'( or have a belly) use either round corner with a bigger radious or draw rays to the edges and make them meet on an edge of a circle then move the circle up a little and it will create the bombe' you want.other way is to make a shallow dome intersect with a rounded corner box and remove the exess. now for the arms and the back extrude them using the cross section of the arms which consists of a rectangle an 3/4 of a circle. extrude this profile using a wide u-shaped path but filet the 2 corners of the u shaped path before using the follow me tool. now you want to make the capitone' recessed buttons ..it is easy. drow small circles at the exact locations of the buttons according to the pattern you want. then offset each circle about 5 or 6 cms ( this is the radious of the recess of the button) then connect both the inner circle and the outer one with random rays then pull down the inner little circle that represents the button using the move tool ,this will make your capitone' style. for the round detail of the coussions edge use a tiny cercle to follow me the edge of the coussion. for the front of the arms offset the face and use the generated offset as a path for tiny domes with the base of those domes sitting on the face of the arms using copy along path plugin. at the end smooth evrything to your satisfaction then texture with a shiny rinkled black leather texture and use also small domes horisontally and vertically as buttons after texturing them with black leather. for the helmit brass nails on the face of the arms use also tiny domes but texture them gold or brass or bronze texture. and enjoy your sofa
regards
hesham