Easiest that comes to mind is this latch, which is available everywhere. Mounted on outside of run entrance. I drew in red line, a
string that you would attach to the eye of hook. Feed string thru the door frame to the interior of run. Then attach a small ball or something, so the string does not fall out of the hole in frame. It can also just be fastened to an eyelet inside run frame.
Where I marked an
"A" is where you can install a padlock for the night, or just a snap clip.
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