Make a Simple Sims 3 Pattern
You will need Delphy’s pattern packager from here, for that to work you will also need .NET Framework 3.5 from here.
You will be working with DDS files so will need a DDS plugin for your paint program.
In your paint program make a new image 256x256 pixels, colour this in bright red, then add a pattern in green and blue.
Make the pattern smaller and then repeat, so you get the same pattern a few times, about 2 - 4 works well.
When you’re happy with it save as a DDS file.
Open up the Pattern Packager, fill in the requested details. Give your pattern a name and import your new DDS pattern file.
Choose some colours for your pattern, this is how they will appear in game, they can be changed, but this is how it will look.
Save your file and then place it into MyComputer/C:/ProgramFiles/Electronic Arts/TheSims3/Mods/Packages/Patterns
When you load the game your new pattern will be in the category you chose for it.

Poppy
Sims