Magnetic door latch

So we have goats, one of whom refuses to be a "scapegoat" but instead is an "escapegoat"! And on top of being a jerk, she most recently closed the door to the hut the herd lives in, and somehow (despite only have 2 fingers) threw the deadbolt locking her friends inside while she jumped the fence and ran around the barn. So we needed a latch to hold their door open (but it had to be easily closable by a person). So I made up a pivoting holder that contains a pair of these [30mm epoxy coated magnets] (https://www.amazon.com/gp/product/B07FZ2VMG8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) (each one with 18lbs force!). The model is designed to use a 4mm button cap M4 bolt going as the hinge pin. Originally I tried tapping the bottom hole but discovered it didn't work particularly well, so ended up using a [4mm long M4 heated brass insert] (https://www.amazon.com/gp/product/B07MWBJB67/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) (put in with a soldering iron). Worked perfectly. I