I use the plastic sheets that come in a package of bacon for template plastic. Just be sure to give it a good scrub with dawn soap. I also use a large muffin tin for sorting thing like buttons, pins and clips. Empty square tissue boxes make great collection boxes for trimmings from batting that I later use for pin cushions. A must have is a collection of assorted sizes of plastic storage bags.
One of my most used unusual items is a smooth fist size rounded rock from the garden. It is a paper weight, presses seams, small hammer and anything else that comes to mind at the "moment" I am looking for something to use.