Built a lowered acustic ceiling segment in my living room, with 20mm x 20mm aluminum tubes as edges.
These are designed to be clipped on the edge, and form the cable management triangle in the middle. Two versions, hook design differes based on the direction of the reel tension.
Can find the pulleys from amazon for example.
This item is a part of a bigger multi-use home cinema / virtual reality livingroom acoustic ceiling element. Check out the collection of other related items.
https://www.printables.com/social/255371-nerdaxic/collections/154159
The author hasn't provided the model origin yet.