T-hinge (aka Tee-hinge). I printed this in ASA for outdoor use as shown in the pictures.
I used these cupboard joining bolts for the hinge itself:
https://www.amazon.co.uk/dp/B0BQ76VW4T?psc=1&ref=ppx_yo2ov_dt_b_product_details
The author marked this model as their own original creation.