Inventor
Inventor is a great tool to create things to be 3-D printed, it is easy to understand and easy to build.
Steps To Using Inventor Successfully
Step 1: For the first step you have to create a 2-D sketch on the XZ plane otherwise known as the horizontal plane.
Step 2: For step 2 you will want to use the line tool to make a shape that resembles one side of your object.
Step 3 includes extruding your object and adding the other criteria like the hole in the center.