pipe.jscad

// all measurements in inches, because AMERICA

function main () {
    // standard 4" sewer pipe
    const innerRadius = 4/2;
    const outerRadius = 4.215/2;
    const length = 20 * 12;  // by "6m" i assume you mean 20ft?
    return difference(
        circle({r: outerRadius, center: true}),
        circle({r: innerRadius, center: true})
    ).extrude({offset: [0, 0, length]})
    .rotateY(90);
}