Engine because he is the one who made it burn the and convert it to energy so the car operates. Now our body can be resembled as car which receives fuel (food and drink) to convert it to energy (calories) and it hen our body function properly, so who manufactured our body? Is it the Mother Nature? What is the definition of the Mother Nature ? Where did the Mother Nature came from? Did it come from nothing?
Forget the above questions, as the main question to you Thelonius is can something be manufactured repeatedly without understanding?