There's DIY and then there's something like Eric Dalpiaz's project, recently highlighted over at Plastolux; what looks like a store-purchased modern seating solution is actually a hand constructed DIY project made from hardwood, an MDF frame, foam, and topped with Knoll upholstery. From what we can tell, this looks as good as any modern furniture piece one could purchase in store in construction and finish...
The ability for it to breakdown in pieces makes it a little easier to move. Its still a bit heavy, the design could use some tweaking to make it a little more lightweight. I wanted to make sure it would last quite awhile. Kind of like that coffee table. The upholstery is from Knoll and does have recycled content, and the mdf is of course nothing but sawdust, so I was trying to keep 'green' in mind as best I could at the time. I did detailed drawings that even laid out all the cuts to reduce the material and waste. That worked out very well.
The seat straps are elastic. The frame is hardwood. I got all the foam precut, and then had an upholstery place glue it down and finish the upholstery. Turned out pretty well and is comfortable considering the shape. Its very deep, deep sofas are more comfy and makes it good to kick your feet up and relax. Sits four easily, or even two people laying side by side with the depth. Hope you enjoy, many people have seen it or sat on it, seems to be a crowd pleaser. If you can't find anything you like or can afford, make it yourself!