How would you draw this?

[Roxy]

Note: I didn't see what 3dkarma posted until after I started making this. The files he posted are really nice. I decided to leave this post because this OpenScad code is much simpler and easier to understand. But if you are actually going to do something like this, the files 3dkarma pointed to are much better!!!!

If you plug this into OpenScad:

pully();

module pully() {
    difference() {
        cylinder(h=15, r=30, $fn=25);                    // main pully block

        translate([0,0,-.1]) cylinder(h=25, r=4, $fn=10);        // drill center hold

// add a path for the wire connecting the balls on the chain
        
        translate([0,0,(15/2)-(2/2)]) difference() {
            cylinder(h=2, r=32, $fn=20);    
            cylinder(h=2, r=29, $fn=20);    
        }

// add holes for ball chain  ---  assume 25 balls fit around the pully
// also assume the balls are 2mm in radious

        for(i=[0:360/25:360-.1]) {                
            rotate([0,0,i]) translate([30,0, 15/2]) sphere( r=2, $fn=15);
        }

    }
}

You will get something that looks like this:


Ball_Chain_Pully.jpg