Who sad that empty cans were of no good? And that you should probably through them off or put them out for recycling. Yes, recycling is a good option but still when you can recycle the item for your own benefit instead of sending the item outside for someone else to use then that will be a total loss. Many geniuses now have covered youtube with tons of DIY videos that are pretty darn easy as well as useful. If you are indeed short at budget you should basically look in for such videos to learn how to recycle something up to get benefit out of it.
This guy particularly designs an insulator/heater that can be best at times of power outages during winters or when you are out in the woods at night. The tools that you need are nothing but simple. An smpty soup can is required which is readily available in every home then you need an empty toilet paper roll, which by the way is a complete necessity and the final ingredient to complete this peel is 70% isopropyl alcohol solution. Not only is this trick a very good deal to produce some heat but this damn thing can also be used to create a stove when you’re out somewhere in the woods.