i had an idea for an invention of a 360 degree treadmill that requires no electricity and can fit under a bed. have yo uever heard of track balls, if you get a bowl like shape that isn't as curved like a bowl but more like a satellite dish and you align the inside of the bowl thing. you could walk on it in any direction and the slope of the bowl added with the movement of the track balls would make your feet slide back into the same place every time. now that you got the directional problem solved you can run an any direction basically infinitely without worrying about hitting a wall. now the only thing you need to do is find out how the VR headset would track your feet. well i got that planned out to. if you add a sensor under the panel of the bowl-shaped thing and if you have two Bluetooth devices that track your feet as you walk so it picks up your feet moving on the sensor then add the data to the headset and bam problem solved. sorry the typing is not worded as good as it could've been i've been working on this idea for a while now if you need help than contact me for more details