I don't think you're going to get a response that will be as close to what you're looking for as you prefer. You really have 3 considerations to deal with. You need to select a material that is capable of moving the water at a speed that allows the irrigating to go on over a fairly sustained period. Since it will need a wick that is only capable of moving water extremely slowly, you must take evaporation into account. You'll need to have a cover or shield to cover the wick to prevent all or most of the water from evaporating before it reaches the plant.

I won't say that your idea isn't practical, but I think you have quite a bit of experimenting & tinkering ahead of you to bring it to fruition.

Al

I also found an old post on this subject that sounds helpful.

A quote from this post "...That is why I now recommend the tent tie down (parachute type) cord as the best I have found to date"

Hope this helps!

Here is a link that might be useful: Water Wick Info

We found the perfect water wick - a 12 year old girl from the neighborhood!

Of course that's the best wick :) But I don't have family close enough to make it worthwhile to drop my plants off to them, nor do I know any of my neighbors well enough to want them coming into my house.

I used old cotton shirts. The difference in water movement is the thickness of the wick. The shrink wrap certainly helps keep the wicking action where it should be. Hanging coco lined baskets dry out fast and these will buy me at least a day on the small bottle system and at least 2 days on the gallon system. In other on ground containers it will certainly add up to a bigger window. I am sure a glazed pot 3 gallon pot with good water holding soil would last a week.

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All the small bottles now have feeder hoses like my initial prototype.
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the materials used were a 12oz water bottle, sleeve from an old cotton shirt, old hose, yogurt container funnel, old blue berry bush container, reusable twist ties and shrink wrap growing a volunteer Roma seedling found in a cold compost pile. The wick is fully in the bottle runs down the side into the soil. Since the other two sit above the wicks were shrink wrapped before reaching the soil.
One of my wicks is made from cotton balls wrapped by burlap.