length = 10;
height = length/16;
kerf = 0.015;

module triangle_side(l, h, kerf) {
    pl = h/tan(30); //peak length
    intr = sqrt(h*h+pl*pl)/7; //intrude length
    js = 1/3; //fracture after which the joint starts
    je = 2/3; //fracture after which the joint end
    d=0.05; //joint thickness along the edge
    k=0.1; //joint intrude
    polygon([   [0-kerf,0],
                [l+kerf, 0],
                [l-pl*js+k*sin(30), h*js+k*cos(30)+kerf],
                [l-pl*js-intr*sin(30)+d*cos(30)+k*sin(30), h*js-intr*cos(30)-d*sin(30)+k*cos(30)+kerf],
                [l-pl*je-intr*sin(30)-d*cos(30)+k*sin(30)+kerf, h*je-intr*cos(30)+d*sin(30)+k*cos(30)],
                [l-pl*je+k*sin(30)+kerf, h*je+k*cos(30)],
                [l-pl+kerf, h],
                [pl-kerf, h],
                [pl*je+k*sin(30), h*je-k*cos(30)+kerf],
                [pl*je-intr*sin(30)+d*cos(30)+k*sin(30), h*je+intr*cos(30)+d*sin(30)-k*cos(30)+kerf],
                [pl*js-intr*sin(30)-d*cos(30)+k*sin(30)-kerf, h*js+intr*cos(30)-d*sin(30)-k*cos(30)],
                [pl*js+k*sin(30)-kerf, h*js-k*cos(30)] ]);
}

triangle_side(length, height, kerf);