I didn't receive the prop guard for the X4 and after 5 min of trying to fly or more accurate, 5 min of crashing, I realised I needed it bad. I tried some of the versions found her at thingiverse but non fitted that well. I think they are made for another version of the X4, so I made a new one. I haven't tried it extensively but it has survived a few close encounters with about every wall in my room. It might come lose from the motor if crashing hard so keep an eye on it. I have added a second version of the guard that should help protect the props when landing(crashing) upside down. Happens surprisingly often. Ok, made a new version. Made the guards on top 5 mm higher. Also open up the ring around the motors and made the holes smaller. This should give a tighter grip. If this is not enough it should be possible to heat up the plastic and close the holes even more.