Edit a .ppam file for customizing an add-in

If it's a PPAM file, it was created in PowerPoint from a PPTM file saved as an add-in.

While you can edit loaded add-ins "in place" for testing purposes, you can't edit then save them. But you can export the add-in's modules then import them into a new PPTM file or copy/paste code between the two.

In order to get access to the modules/code of the loaded add-in, you need to make a registry change.

IMPORTANT: Quit PowerPoint first.

Then go to:

HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\PowerPoint\Options

(That'd be for PPT 2010; substitute 16.0 in place of 14.0 for PPT 2016/365 and PPT 2019, 15.0 for PPT 2013, 12.0 for PPT 2007 and so on ... there's no 13.0)

Add a new DWORD value: DebugAddins = 1

Start PPT again; now your loaded add-ins will appear in the VBA IDE. If they're not password protected, you'll be able to open them, edit for test purposes, and export the modules or copy/paste for use in a new PPTM file.

Be sure to export any modules you've changed fairly often; if you quit PPT or it crashes, you'll lose any changes since the last save.

If you also want to copy/modify a custom ribbon

In addition to Steve Rindsberg's perfect solution, you can do the following to transfer custom ribbon properties:

1. Start off from the original .ppam file and the modified .pptm file as described in Steve's post. In the following, I'll refer to them as OLD.ppam and NEW.pptm.
2. Open both OLD.ppam and NEW.pptm using Office RibbonX Editor.
3. Under the NEW.pptm file, add a customUI14.xml entry by clicking Insert --> Office 2010+ Custom UI part.
4. Copy the contents from the customUI14.xml part of the OLD.ppam to the one within NEW.pptm.
5. To get the icons: Extract the OLD.ppam file in the Windows Explorer using 7zip or similar. You'll find the images within the extracted folder OLD/customUI/.
6. Back in Office RibbonX Editor, click on customUI14.xml within NEW.pptm. Then, insert the Icons from the Insert menu. You can select all items at once.
7. Save the file NEW.pptm in Office RibbonX Editor and close it.
8. To create an add-in, open NEW.pptm in PowerPoint and save it as NEW.ppam.