D) Get the school involved. Schools can be a great resource, if you are an individual or group, to get involved as you can work with the entire school or perhaps the specific departments (like art, science, engineering). Sometimes big schools even have their own recycling programs.
If you are the school, ask your students to start collecting at home and ask other teachers to get involved. You might inspire the art department to infuse trash into their creations. A science or engineering teacher or department might be able help figure out ideas on how to literally create new materials out of certain collected items. Perhaps you can start your own recycling program at the school that helps serve all future Trashion shows. If you have a recycling program already, work with the head of that program so you can sort through or put aside particular items that will be useful to trashion design.