Well, it's not so much an experiment as a 'try a bunch of new stuff and see what happens':

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This is just a basic 3.5 gallon inside a 5 gallon bucket SWC, with a couple of twists on the usual designs.

First big difference is that I'm trying wicks instead of a wicking chamber. I experimented with wicking chambers a bit over the winter, and played around with different ways to be able to adjust the amount of wicking both in the design and 'on the fly'. The wicks are made from strands cut from a rayon mop head:

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Al recommends these for draining wicks so I'd already picked one up (Mainstays brand at W-Mart). A single strand wicks a fair amount of water, so I'm trying 6 to start with, and will either cut them off or tie them out of the way with fishing line to if they wick too much. If they fail to wick enough I'll top water.

Next difference is the 3.5 gallon bucket insert:

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Yep, I drilled all them holes. I noticed that these buckets (Letica brand) fit fairly loose in the 5 gallon Lowes bucket. One of the supposed benefits of most SWC designs is that the roots get better aeration from holes in the soil bench. I've also read about the benefits of fabric 'smart pots' and air root pruning, so I thought I'd give this a try. It may be too humid inside for real air root pruning to be a benefit, but we'll see how it works. I kind of hope it doesn't offer any benefit as drilling all those holes was a drag. Remember, the inside bucket is a loose fit, so there's a small air gap on the sides. This wouldn't work with identical buckets that fit snugly inside each other.

I used 1/4 inch holes and just fed the wicks through. A loose knot kept them in place nicely:

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Here it is assembled:

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The fill tube is from one of last years SWC so it's a bit long for this unit.

I'm trying out a mix based on one of JustaGuy's suggestions, 3 parts partially composted pine bark fines and one part turface (in this case unscreened NAPA floor dry). I also added a cup of garden lime and a little bit of Osmocote:

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I don't have the reservoir filled yet, as I'm planning on top watering until the plants are a bit established. One of my Taichung Snow Peas sprouted faster than expected so I decided to plant it today:

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It's still a bit early, so a 5 gallon jug with the bottom cut out will act as a cloche. I tied it the handle of the 5 gallon bucket using a 'truckers knot' on one side so it can removed as needed:

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Once the jug is no longer needed I'll add a bucket lid and tomato cage for the peas to climb like this:

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Sorry for the sickly tomato pic, if it's any consolation it recovered quite a bit and produced some nice fruit.

Last year I used landscape fabric on the bottom of all my SWCs to keep roots out and potting mix in. I suspect that landscape fabric may slow down soil bench aeration, and may contribute to extra perched water at the bottom of the mix. Some SWCers don't bother with this step (including most of the commercial units), so I'm thinking of also leaving it out this year. I was concerned that with this loose mix and these holes that a lot of mix would spill into the reservoir. Some mix did spill through the holes during filling, but it was only a little bit and was easy to clean out.

If this setup works out I'll make some more to transplant early tomatoes next month.