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[pixelated]

That Extend-n-Click seems to be the only extension with a built-in shutter control.  For the other extensions, you can use a wireless remote like this one:
Muku Shuttr - Selfie Remote / Camera Shutter for iPhone, iPad, Samsung, LG, Android and Nexus
http://www.amazon.com/Muku-Shuttr-Shutter-Frustration-Packaging/dp/B00JK5OW8C

[eyore]

tempting, very  tempting - actually says it works with iPod touch (and I know the bluetooth works on my iPod as a have a Bluetooth player). Around £20 here - cost of 2 DVDs or 2 packs of cigarettes. As I find lifting my arms up difficult now and the cameras feel heavier, that's a definite possibility.

[pixelated]

One of the answers to a question ("Will this work with third party apps such as Camera for iPad?') is:
"It works with camera apps that support the volume up switch as a shutter. When you press the Muku shutter it operates the iPhone's or iPad's volume up switch."

You should be able to test that functionality on your iPod before you order the remote.