Around 300 million people in the world do not have access to clean drinking water  with simple 3d printed parts and a 250ml that could change       this design allows for a water filter to be made inside the can by layering gravel, sand and charcoal and allowing them to filter out impurities    this desing has threaded end that can be glued tothe can the allow the threaded caps to be removed for cleaning of the filter or to be re-used with another filter system     the caps can also thread onto a standard water bottle on both ends to make filtering easier and can be left upright to do its thing     this is prortable and optimized for 3d printing     you can run your water through it as many times as you want then boil the filtered water to ensure the water is clean and bacteria free        3d printed parts may not be the best option for consumables but in a pinch it can make the difference between life and death