Most of the people reading this blog have friends or friends of friends who are mechanics and very skilled at repairing cars or othre machines. And if you are a mechanic it is a must to have an old engine that doesn’t work and just sitting useless somewhere. So ask them if they can give/sell the old engine they don’t use in order to create a coffee table!
Probably before using the engine you need to clean it, maybe paint it to look nice. After that, what you need to do is to buy a round or square glass to put on top of the engine. And it is finished! Easy right?