The aruino-based astronaut costume I made for my son was a huge hit:
https://www.youtube.com/watch?v=eP8UbU3VrGQ
Main Components:
2x arduino uno
1x sound board
1x power boost 500c
1x tft cap touch screen
6x neopixels
2x white led backlights
Started with an astronaut costume and helmet I bought on Amazon and printed a bunch of 3d parts (PLA and Ninjaflex) to make the chest pack, headlamps, and wrist computer. I had most of the components except the sound board and touch screen. Fun project.