What are really good insulators that are common items you can find or buy at stores?

What are really good insulators that are common items you can find or buy at stores? i am doing a project where you use a plastic container and put insulation in it to keep a fake bug frozen in a ice cube from melting. It will lie under a lamp that is on. What are very good insulators that wont let the heat come... show more What are really good insulators that are common items you can find or buy at stores?
i am doing a project where you use a plastic container and put insulation in it to keep a fake bug frozen in a ice cube from melting. It will lie under a lamp that is on. What are very good insulators that wont let the heat come in and wont let the cold get out? It has to be common so no chemicals, fiberglass and i cant use caulk.