https://www.gobilda.com/plastic-hinge-block-25-pack/

Plastic Hinge Blocks open the door to swivel functionality across a variety of installations. Their on-pattern design allows for a myriad of creative combinations.  Fasten multiple blocks together with an M4 screw and a locknut to create the perfect hinge for your project, or explore non-hinge applications by tightening a bolt to secure the blocks at a specific angle–easily measured thanks to grooves at 45° on each block!