Just a simple catch I printed for holding my sliding polytunnel doors closed against the wind. Was using bent wire before but I wanted a simple, one-handed ergonomic solution instead. Mine is a tunnel from Poly Dome but could be adapted for other similar door setups maybe. 

gcode included for Prusament PETG 0.4mm nozzle with 4 perimeters for strength, practically solid. An initial draft 0.4 layer print with a 0.6 nozzle worked for a couple of months but snapped the ring that usually flexes for opening, probably a weak point in the simple design, I suspect it will fail there again after many flexes.