This is a pulley system designed for use with 5mm umbrella cords
The system needs to be equipped with two M5 screws that are more than 35mm in length, two M5 nuts, and two small washers to ensure that the washers can be snugly embedded between the printed parts and the nuts.
In addition, if a large washer is installed between the two rollers, the stability can be further improved.

It is recommended to print it twice: Block 13042018
It is recommended to print it four times: pulley hub

If you choose the pulley hub 13042018, you can create a pulley hub with a width of 11mm; in this case, there is no need to add an extra large washer
If you choose a pulley hub with dimensions of 20042018, you can create a pulley hub with a width of 10mm. In this case, it is essential to pair it with a large washer with a diameter of 30mm

In the future, I plan to optimize this design by reducing the friction between the wheel surfaces and installing bearings as needed to further improve the performance and durability of the pulley system.