Mainstage makes it a bit confusing to save presets for future use. Here’s how manage my presets so I can find what I need quickly: 

1. Open your Mainstage project. Tweak a patch to match what you need, or build one from scratch.

2. In the patch list section, click the drop down menu. Select “Save As Patch . . .” This will save all of your control mappings, multiple channel strips, and all of your busses into a single patch that you can use in Mainstage or Logic Pro. 

3. Select the destination where you want to save the patch. I put mine in folder inside my Music folder, with different sub group folders. 

4. To import the patch back into your session, you can either select “Load Patch” in the previously mentioned drop down window, or use the key command “command-i”.