Non-Commercial Thermal Insulation
Often the key with stopping the conduction of heat is to provide as many phase transitions as possible. Most thermal insulators achieve this by having voids of Air which is achieved in a variety of ways, bubble wrap, fibre glass etc.

For a "non comercial" I assume they mean stuff you have lying around the lab?

To attempt this I'd layer blue roll / cotton wool / glass wool with tin foil. The more layers the better.