Just as there is 'food for free', fuel and other materials available by foraging in wild space there are equivalents in urban settings due to wasteful practices.
There is an issue of sustainability when humans visit wild areas and consume resources but in our own built environment is the responcibility flipped; is there an ethical imperative to find uses for the waste?
Re-using and repurposing furniture, tools etc.
Legality of removing items from skips and rubbish collection areas, (trespass and property).
Health and safety.
Resources required to remove, transport and process materials.
How will we dispose of our materials when the project finishes?