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Oh, anything about self sufficiency and sustainability, whatever you've got up your sleeves. Are you into Spirulina at all? ;-) Okay, just being cheeky, but please, by all means, whatever plucks the strings of passion. Oh, sustainable toilets of any kind! And companionship: between plant species, animal species, plants and animals... guilds, up to whole ecosystems.
Hahahaha sorry, as you can see, I'm not so good at making specific requests.

I'm not into spirulina...yet. I've heard a lot of good things about it though and may whip up a growing tank soon...

Thanks for the ideas! All fantastic and added to the list.