TBS Zephyr Bungee Launch Hook

Bungee launch hook for retiring zephyr 2 with TBS lipo bay.
Holes are for M4 screws and wired piece is to drill the holes at the right place.
NB: The hobby king bungee isn't enough powerful to launch the ZII !

Please note my design is base on this one:
http://www.thingiverse.com/thing:461214