Project Ideas

I have looked for a long time for some project, that has the special wow effect. I had a look on the internet but did not find the right thing. Therefore I am asking you for some ideas. I have 2 Arduino Uno’s and could get 1 more, if needed. I also have a Raspberry Pi 3 with a screen. One more thing that I already have is a voice recognition shield(EasyVr shield from Sparkfun). I would be willing to buy more stuff for about 50 $.
I know this is a widely asked question, but I really did not find anything until now that has the wow effect and that I actually would be able to build.
I hope for some nice answers.
Thank you guys