You can use the mklink command. It is a bad idea to move all of AppData, just look for the largest offenders. For this example, say your user name is xxx, and the folder is "Amazing Cat Dog" in Roaming.
Step 1. Make sure the respective App is not running.
Step 2. Move the folder. Lets say to "D:\xxx\AppData\Roaming\Amazing Cat Dog"
Step 3. Run: cmd Step 4. Type: cd C:\Users\xxx\AppData\Roaming
Step 5. Type mklink /j "Amazing Cat Dog" "D:\xxx\AppData\Roaming\Amazing Cat Dog".
Step 6. Launch your application and make sure it still works.
Be careful, Microsoft does not recommend this. You could have extremely negative impacts if you mess it up, or if you do this with driver files. But when you have "Amazing Cat Dog" using up 50 GB, of your 100 GB solid state drive, you may have no other option.
If you uninstall the application later, you'll probably have do some manual cleanup.
The other option is to move higher level folders like Roaming by opening properties and changing the Location. I have had limited success with this approach, because first, not every folder I want to move has this option. Second applications will be locking some of the files, so you can end-up with out of sync or duplicate data. Lastly, while you might want to move a folder with 50 GB of data, it is silly to move folders with very little data, as that just decreases your performance for very little gain.