Several different ways to do the same thing

You may have noticed that,while using a CAD program, there are several ways to get to the same result. Also different programs use different techniques to get to the same result. What's the point of this post ? To prove that CAD is much more than a single program or only one drawing technique. Let's create a very simple 3D object, a pipe with 100mm height,outer diameter 20mm, inner diameter 15mm, by several different ways and programs.

1. Primitive solids/ FreeCAD
Create 2 cylinders, edit their data to height 100mm for both and diameter 20mm for the first and 15mm for the second cylinder. Then with the boolean operation "Cut" cut the second cylinder from the first one.

2. Sketch extrusion/ GraphiteOne
With the sketch tool create two circles with same center and then with the smart dimension tool set the diameters to 20mm (r 10mm) for the first circle and to 15mm (r 7.5mm) for the second. Then use the extrude boss/base tool to extrude the sketch and set the extrusion height to 100mm.

3. Automatic pipe tool/ VariCAD
Select the pipe tool from the toolbar, set height to 100mm, inner diameter to 15mm, outer diameter to 20mm and press enter.

4. Drawing Extrusion/ Bricscad Pro
Draw two circles with  diameters 20mm and 15mm and the same center. Extrude both circles with a specified height of 100mm. Then from the "Modify" menu select Solid editing--> Subtract, select the big circle, click enter, then select the small circle, click enter and you are ready.

5. Drawing Revolve/ Bricscad Pro
Draw a rectangle with 10mm width and 100mm height ( Specify the first corner with the mouse and then type @ 10,100 in the command line). Select the same point as a first corner for a new rectangle with width 7.5mm and height 100mm (@ 7.5,100). Revolve both rectangles with the left side of both rectangles as a revolution axis and the revolution angle set to 360. Then from the "Modify" menu select Solid editing--> Subtract, select the big rectangle, click enter, then select the small rectangle and click enter again and you are ready.

As you can see when you work with CAD you have more than one way to do the same thing.

Note: Of course each of the used programs can work with more than one from the above techniques. (For example FreeCAD can revolve/extrude 2D drawings/sketches and Bricscad can create primitive solids). I believe that using different programs is better for this post than using several different techniques with only one program.