OpenSCAD

/*This helper library was originally created by davidIvann and 
can be found in his Parametric Space Truss http://www.thingiverse.com/thing:10642
It allows you to join two points on a plane and add rounded corners
*/
module join_two_points(x1, y1, z1, x2, y2, z2, diameter){
	length = sqrt( pow(x1 - x2, 2) + pow(y1 - y2, 2) + pow(z1 - z2, 2) );
	
	alpha = ( (y2 - y1 != 0) ? atan( (z2 - z1) / (y2 - y1) ) : 0 );
	beta = 90 - ( (x2 - x1 != 0) ? atan( (z2 - z1) / (x2 - x1) ) :  0 );
	gamma =  ( (x2 - x1 != 0) ? atan( (y2 - y1) / (x2 - x1) ) : ( (y2 - y1 >= 0) ? 90 : -90 ) ) + ( (x2 - x1 >= 0) ? 0 : -180 );

	echo(Length = length, Alpha = alpha, Beta = beta, Gamma = gamma);	

	translate([x1, y1, z1])
	rotate([ 0, beta, gamma ])
	cylinder(h = length, r = diameter/2, center = false );
}

module corner(x, y, z, diameter){
	translate([x, y, z])
	sphere( r = diameter/2 );
}
// Axial elements for math checking 
//join_two_points( 0, 0, 0, 50, 0, 0, 5 ); // +X
//join_two_points( 0, 0, 0, -50, 0, 0, 5 ); // -X
//join_two_points( 0, 0, 0, 0, 50, 0, 5 ); // +Y
//join_two_points( 0, 0, 0, 0, -50, 0, 5 ); // -Y
//join_two_points( 0, 0, 0, 0, 0, 50, 5 ); // +Z
//join_two_points( 0, 0, 0, 0, 0, -50, 5 ); // -Z

//join_two_points( 0, 0, 0, 50, 50, 0, 5 ); // +X +Y
//join_two_points( 0, 0, 0, 50, -50, 0, 5 ); // +X -Y
//join_two_points( 0, 0, 0, -50, 50, 0, 5 ); // -X +Y
//join_two_points( 0, 0, 0, -50, -50, 0, 5 ); // -X -Y
//join_two_points( 0, 0, 0, 50, 50, 50, 5 ); // +XYZ
	

$fn=64;

module pipe(innerR=10,outerR=12,bendR=50, quarter=true, half=false){
	difference(){

		intersection(){
			rotate_extrude(convexity=5)
			translate([bendR+innerR,0,0])
			circle(r=outerR);
			if(quarter){
				translate([0,0,-bendR])
				cube([bendR*2,bendR*2,bendR*2]);
			}else if(half){
				translate([0,-bendR*2,-bendR])
				cube([bendR*4,bendR*4,bendR*2]);
			}
		}
		rotate_extrude(convexity=5)
		translate([bendR+innerR,0,0])
		circle(r=innerR);
	}
}
pipe(10,15,40, false,false);

/*This helper file was created by Triffid Hunter <triffid.hunter@gmail.com>
in order to create a bend in a cylinder*/

$fn=128;

radius = 4;
inner_radius = 3.5;

bend_radius = 40;

angle_1 = 10;
angle_2 = 100;

union() {
    // lower arm
    rotate([0, 0, angle_1])
        translate([bend_radius + radius, 0.02, 0])
        rotate([90, 0, 0])
        difference() {
            cylinder(r=radius, h=50);
            translate([0, 0, -1])
                cylinder(r=inner_radius, h=52);
        }
    // upper arm
    rotate([0, 0, angle_2])
        translate([bend_radius + radius, -0.02, 0])
        rotate([-90, 0, 0])
        difference() {
            cylinder(r=radius, h=50);
            translate([0, 0, -1])
                cylinder(r=inner_radius, h=52);
        }
    // bend
    difference() {
        // torus
        rotate_extrude()
            translate([bend_radius + radius, 0, 0])
            circle(r=radius);

        // torus cutout
        rotate_extrude()
            translate([bend_radius + radius, 0, 0])
            circle(r=inner_radius);
        // lower cutout
        rotate([0, 0, angle_1])
            translate([-50 * (((angle_2 - angle_1) <= 180)?1:0), -100, -50])
            cube([100, 100, 100]);
        // upper cutout
        rotate([0, 0, angle_2])
            translate([-50 * (((angle_2 - angle_1) <= 180)?1:0), 0, -50])
            cube([100, 100, 100]);
    }
}

difference(){
	cube([20,10,2], center=true);
	makeHole(5,0,0,10,3,64);	
}
	
module makeHole(x,y,zOffset, height, hole, resolution){
	translate([x,y,zOffset+height/2]){
    	cylinder(r=hole/2,h=height*2,center=true,$fn=resolution);
    }
}