To be honest I'm not much of a DIY person on my camera. I'm Ok with using a DIY soft box or some other non invasive stuff...
Imagine this: a 1000 usd setup (if not more) with a pringles box!!!
It could be safe but I would feel embarassed to carry such setup in public.
I guess the price of the camera cover as well as the lens cover used would be around 10-15 usd which is close to the price of one of the extension tubes which you can buy separately. I guess the price of a single extension tube or the whole set, is a minor investment that provides good results.
That is not to mention the risk of the whole setup (pringles one) detaching and dropping your lens, which would cost a lot more then. or the risk of scrathing your lens or body.
Still as I said before all of these would be really limiting on depth of field and working distance and I suggest that yo utake your camera and lens with you to a camera store and try them before buying any.