There is a workshop
to create your own custom content for sims 3 and 4. It's called TSR workshop.
It's a free download software found on the link above.
Here is tutorial youtube video to help you use the workshop:
Really will benefit your games. ENJOY
You'd have to extract (unzip)the downloaded folder of TSR to get it work.
Simple right click and it's listed on drop down menu. Follow the installation and then get designing.
Tells how to get TSR to work here:
Don't worry it's only a bad day, not a bad life.