My child is now 5, so I have a lot of Junk-Free Birthday Party posts to catch up on. When my son was 3, I had this simple little party for him. I made the backdrop of Metropolis out of large poster size cardstock (is that the right word? I am so not a Pinterest expert here) and just used glue and scissors.. not perfect but so beloved, it is still on his wall in his room (see pic below). This was a very simple afternoon party, super easy and small, low-cost.