Nothing wrong with found objects to speed up the mockup, need a ring, bottom of a can of soda, need a cool curve, look around find a plastic jug and your hot gun and bang it out. Two things, to remember when in doubt paint the whole thing white, noting tells the truth of the form like a monochromatic white paint job. The other thing, do it fast, so you are NOT reticent about chopping it up to make changes.