Distanzhülse M4 mit Bund, 12 mm

// Abstandshalter / Distanzhülse für Schraubverbindungen.
hoehe    = 12;  // Höhe der Hülse (mm)
d_innen  = 4.5; // Innendurchmesser, z.B. M4 mit Spiel (mm) [1:d_aussen-1.6]
d_aussen = 9;   // Außendurchmesser (mm) [d_innen+1.6:bund_d]
bund_d   = 12;  // Durchmesser des Bunds (mm)
bund_h   = 2;   // Höhe des Bunds (mm)
$fn = 64;
e = 0.01;
difference() {
    union() {
        cylinder(h = bund_h, d = bund_d);
        cylinder(h = hoehe, d = d_aussen);
    }
    translate([0,0,-e]) cylinder(h = hoehe + 2*e, d = d_innen);
}

This is exactly the source behind the sliders above – the parameters are the named variables in it. You can open it locally in OpenSCAD and keep writing; you are not tied to anything. Download the SCAD – no account.