Ok, let's play do this imaginative exercise - Hammer looks simple but actually if you're few inches off while slamming it down, you can seriously injure yourself if you're holding the nails with your other hand. I'm sure we have all experienced that. How about a sensor that always drives the motion in the right location, it can be done by having sensors that feel your muscle twitches and angle then recalibrate using camera to the right angle and nails it in (pun intended). Another idea is a Swiss army knife but something that combines hammer, screwdriver, wrench into one design design offsetting the need to by separate tools.