When you don't want a hinge showing on top and there's no back panel to mount to, this hinge will mount on the side of the box, inside.

Pivot holes are 4mm intended for snug fitting M4 bolts & nuts. Mounting holes are 1/4" intended for 3/16" wood screws.

I have provided "left" and "right" model files for those with smaller build plates. The "both" file pretty much fills the 200mm build plate of the UM2 with the "adhesion" set to "brim" (recommended).