Blender 2.79 3D software is very powerful and truthfully way more then what is needed for create your own custom content for Sims. The reason everyone uses it is really simple, Blender is FREE. You will be able to find lots of great tutorials on YouTube and in your Google searches to help you along the way.
I thought i would share some of the tips and tricks I have learned over the last couple of months working with Blender 2.79. This is really important to remember only use Blender 2.79 or lower when making Sims 4 CC because these are the only versions on the tool that are currently compatible with Sims 4 studio. Blender is used the model the 3D objects you create and Sims 4 Studio is used to take that model and the overlay colors to create the file needed to add into your Sims 4 mod folder in your game. You will also need to have a program like Adobe photo shop to edit the texture to add color to your item. Creating your own CC is time consuming and does require these 3 programs but i have fund it to be really fun and exciting to see something that I have created in the game.
Warning Blender is based in hotkeys and you will have to learn many of them to be able to move and work with the objects. The main hot keys are A, S, U, X, Shift, R, E, and Space bar to search. You can find a full list of hotkeys in Blender under file then user pref and inputs.