This is a belt spanner and a belt mount for a heatbed on the Creality CR10-S5 that has been raised by 20mm to allow clearance for a dual belt y drive.
The belt mount should be printed in ABS for maximum heat resistance. The spanner was printed from PETG-CF for heat resistance as well as stiffness, but ABS should also work fine.
They use some standard hardware (screws, washers, etc.) and brass heated inserts for assembly.
For the motor mounts see https://grabcad.com/library/nema-17-stepper-mount-plate-on-creality-cr-10-s5-1
Also see this article for other parts, photos and a german description: https://konstruktiv-berlin.de/2023/08/24/verbesserungen-am-3d-drucker-cr10/
The author marked this model as their own original creation.