https://www.youtube.com/watch?v=5DumofDtrPM "Ping Pong Popper" (named by our nieces, nephews and grandkids) is an easy to make 3D printed toy for the young ones (and some old ones) in our family, and they all love it! Just two 3D printed parts, a spring, some string and a ping pong ball saves the grandparents / aunt / uncle (my wife and I) around $25.00 USD for a trip to the local indoor pizza parlor / arcade in an attempt to win one of these. And if we do win one, well, they're broken within an hour. Now I just print another (the green Ping Pong Popper is for my youngest grandson Gabe)! As usual, I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to point them out as I do make mistakes in plenty. Designed using Autodesk Fusion 360, sliced using Cura 3.5.1, and printed in PLA on an Ultimaker 2+ Extended and an Ultimaker 3 Extended.