Roughly two weeks' worth of cans collected from residential waste that have been diverted from conventional waste collection.
These cans require some preparation before use, including emptying, cleaning, puncturing, and straightening. Sorting is important, as uncrushed cans are more valuable than fully crushed ones.
If you plan to fill the cans with soil structure material, you may choose to open up the top of the cans using a tinsnipper. This involves cutting a few snips from the opening towards the outer edge and then using the tinsnipper to fold down the sharp edges. It is important to exercise caution when performing this task and to consider other easier and safer methods of filling the cans, such as using a funnel and smaller materials that fit through the existing opening.
It is essential to preserve the cans' structural integrity as much as possible, as uncrushed, full cans offer the greatest strength. However, there will always be gaps, and these spaces are where air, water, and roots will grow.