So I ended up getting the Hyperion 5200mAh extended battery off amazon.
Then I purchased the Otterbox Defender case from amazon.
Things you will need:
-Dry erase marker
-and about 30 mins of your time
Here is my step by steps:
1. I took the otterbox and cut a small hole with the dremel (basically the inside where there wasn't the soft pad)
2. After you cut the start hole it will allow you to line up the case to the phone with the extended battery in the phone. Then trace out then hole with the dry erase marker to the battery. Once you have traced it then removed the battery and line up your trace marks and flip case over holding the battery and trace the inside.
3. Once you cut it test fit it to make sure you don't need to trim any more.
4. Now you need to trace and cut the same hole on the stock back case so the phone will set properly in the otterbox. So trace and cut that case just like you did the otterbox.
5. Once both cases are cut, put phone back cover on, and otterbox, and insert battery.
Now continue building the case.
That's all there is too it. Some finished pictures and comparison to extended battery case.
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