favorite mug is the best for breaking the laws of physics and generating infinite energy - though the blanket and the candle also have infinite heat, the mug would be the most versatile, as you could fill it with a super-hot liquid, then treat it like an RTG, generating electricity from the temperature difference between the mug and its environment. use the mug as your spaceship's power supply, and you'll never even need big honkin photovoltaic panels !