Skywatcher Star Adventurer 2i Custom Battery Door.
 
*Tracker, tripod head and other accessories not included.
 
BACK STORY:
Aligning the tracker can be a daunting task, and you need good alignment to be able to get a good astro image with the tracker. iOS has an app called PS Align Pro, when you manipulate the phone the bullseye target allows you to find the South Celestial Pole, this is why I needed a flat surface to mount my phone to top of the tracker. With the original battery door, you need to press your phone to the flat surface and move the tracker around, it’s as awkward as it comes and I’ve dropped my phone countless times.
 
After about 4-5 test prints, cutting, melting, sanding, etc. Countless back and forth with my printer/3D designer about changes. I am now happy with how it looks and how it performs. A large rubber lined flat surface allows the phone to rest without moving while you manipulate the mount to get the right alignment via the app.
 
HOW TO USE:
1. Put your phone on the mount.
2. Open up PS Align Pro app, choose the Sigma Octantis
3. Move your mount (pan and tilt) until the red dot is in the centre of the bullseye.
4. You can use the scope to find the Sigma Octans and fine tune your alignment. (I don’t find this step to be necessary if I am doing wide field or even at 100mm).

This is certain to polar align in less than 30sec, where as the traditional method is usually more time consuming and can take up to 5-10 min to do so.