I stopped hanging out in /r/DIY before /r/DIWHY became a thing, because it was turning into a roast of people risking life, limb, and property by doing something structurally unsound. There's educating people on building standards, and then there's just bagging on people.
In an attempt to be more of the former than the latter, if the string or especially that strut sheer off of their mounts, that whole contraption is slamming down. Your groin is pretty well protected, but you can still catch that upper bit in the teeth. Figure out how far stuff should move and add stops to keep it from going a hair farther. Replace most of the nails with bolts (beware of end grain, which can split, in which case nail/bolt makes little difference).
Aside: My personal favorite trick that doesn't get used enough is eddy currents. If something has to move easily but not too quickly, a piece of aluminum, copper (or I think non-ferrous steel?) and a rare earth magnet will decrease the terminal velocity of the moving bit. You still take a hit, but you might walk away from it.
In an attempt to be more of the former than the latter, if the string or especially that strut sheer off of their mounts, that whole contraption is slamming down. Your groin is pretty well protected, but you can still catch that upper bit in the teeth. Figure out how far stuff should move and add stops to keep it from going a hair farther. Replace most of the nails with bolts (beware of end grain, which can split, in which case nail/bolt makes little difference).
Aside: My personal favorite trick that doesn't get used enough is eddy currents. If something has to move easily but not too quickly, a piece of aluminum, copper (or I think non-ferrous steel?) and a rare earth magnet will decrease the terminal velocity of the moving bit. You still take a hit, but you might walk away from it.