Ask HN: What's the coolest physical thing you've made?
I made a baseball bat that uses explosives to add a bunch of energy to your swing and hit a baseball really far. It uses the explosive blanks normally used to shoot nails into concrete (e.g. ramset). It worked way better than I expected, didn't have a kick, and turned out to be just a really neat thing to look at while sipping a frosty beverage. I also made a video about it if you're interested: https://youtu.be/Puo6Vgcbxps