The art wall
The art wall is a place for people to share their thoughts and feelings, whether that's through pictures or words. Imagine a blank wall that isn't in a busy area, two suggestion boxes and a paper dispenser.
One box can be for thoughts/venting, which would be disposed of regularly by whoever is responsible for the wall. Sometimes people just need to get their emotions out on paper but don't actually want anyone to read it, kind of like a confession box.
The second box can be for inspirational art that doesn't have to be artistic Mona Lisa type, just something that makes people happy. These would be checked and the appropriate ones would get put on the wall for people to look at as they are passing.
If you don't think there would be much response then just pick a smaller section of a wall.
The budget can vary, from cardboard suggestion boxes for less than £10, and memo blocks in plastic casing for around £5 plus some Blu Tack and straight onto a wall, all the way up to metal letterboxes with keys, a Perspex board, tamperproof noticeboards, etc, for £200+