Simple piston-ring-pusher tool to help with measuring gaps repeatably. Requires https://github.com/revarbat/BOSL2 for the chamfer.

ring_thing.scad

include <BOSL2/std.scad>

$fn=500;


difference() {
    union() { 
        difference() {
            cylinder(h=25, r = 50, center = false);
            up(25) #chamfer_cylinder_mask(r=50, chamfer=2);
        }
        cylinder(h=5, r = 60, center = true);
    }
    cylinder(h=100, r = 40, center = true);
}