Autodesk inventor is a software that allows you to design and create parts online before the actual production. In inventor you can make and design singular parts. You can also do an assembly which allows you to put multiple parts together to make sure they will fit and work the way you need them to. in addition, you can use your inventor files in 3d printing software in order to 3d print the part or assembly.
Here I will be using SketchUp as a replacement for inventor in order to make a step by step guide to making a widget.
Step 2 is to click on create new and then simple template-feet and inches on the homepage.
For step 4, draw the horizontal and vertical lines shown. After that draw the diagonal lines to the intersection of the perpendicular lines. Then you can delete all the guiding lines so just the main shape is left.
This process can be applied to any of the widgets shown.