After you get your gloves you need some kind of lubricant. I've heard a lot of things for this and looked everywhere for the perfect lub. In my research I've found vasilne, spit, water, KY which is awesome, and baby oil. All of these work just fine. They'll do the job of making your green stuff no stick. The biggest challenge however is after you work your green stuff into the position you want you then have to get it to stick to your model. A lot of the oils fall short on this because you'll have to wash it and unless you're really good you might lose some of the detail you so painstakingly worked for.
This is when one day when I was working with some green stuff and was trying to figure out soemthing I had around the house because I was just tired of water drying up so quickly. It was then I looked across all the clutter that is my paint desk to see my personal green stuff savior: Flow Aid. Its great, it drys on its own, its viscous, it doesn't leave any weird film, it doesn't alter the greenstuff and it can be patted dry cleanly. I got my bottle of it at the local art supply for 8$. I don't imagine I'll need to buy a new one soon and I do a fair amount of green stuff work now.
Now for the record, I know this stuff isn't for green stuff. Its original use is to increase the flow of paint and to smooth the surface of brush streaks. That doesn't stop it from being awesome.
I digress... Making chains. First start out with two equal portions of green stuff from your yellow and blue tubes. I prefer a little more blue, I really have no justification except I find it holds its shape better and is a little firmer. To be 100% honest, I can't remember which one is the clay and which is the epoxy but I can remember which one I like to have a little more of and its the blue. After you get your two semi-even pieces mix them up. I put them side by side and twist until they're decently mixed then I just roll it around between my palms. Whatever works for you works. Work it until its a solid even tone of green.
After you get your piece let it sit for a little while and it'll firm up. Green stuff usually takes about a day to cure so you can let it sit around for about 20-30 minutes for it to become a little more firm. For this tutorial I didn't do that, but it shows that you don't need to but I know my end product would have looked better and not stretched had I let it cure that extra time.
Drop a bead of flow aid (FA) on your work surface and streak it with your finger. Seperate out a b-b sized ball of green stuff (GS) and work it into a thick cylinder in your hands. After that work the GS on the work surface while rolling it in the FA into a very long, very thin string make it about 1mm or as small as you can. The thinner you make it the better your chain will look but the more difficult it'll become to do long lengths of chain. Be care to support the ends down and work by putting pressure in the middle and out towards the ends. If you put pressure on the end and work inward you'll create a bump and end up twisting the string on its self.
After you get your string made, cut it in half and try to make it just a little thinner just to push that boundary. You could just make two smaller ones but I find that I end up making it two long any way and still have to cut it in half even if that wasn't my intention. Long story short; end up with two very thin lengths of GS that you want to be about the size of your chain.
Now comes the tools. Its very important to keep your tools lubricated to avoid the GS sticking to your tools. The biggest tool I use is my smoothing tool. I'm not sure the exact name so I just call it my smoothing tool because it smooths. It has a flat angled side and a round conical shaped opposite side. For this, we'll use the conical side.
Lay one of your stings flat and straight on the work surface. make sure your still lubricated under it for when you want to pick it up off the surface in the end to put on your model. I do this by putting a bead of FA at one end and then just streaking it with my finger down the work surface.
After your GS is in place slowly and carefully put tiny indentations with your smoothing tool down the length of the string. Make them about .5mm apart.
Once this is done, try to pat the surface dry to get any excess FA off the GS being careful not to lose your holes you've created. Your holes need to be deep enough that they've buldged the sides out creating what looks like a bunch of 8's stacked on top of each other look. After you've patted it dry very carefully lay your other string on top of the 8's.
To get this as straight as possible I'll put some FA on my index finger and thumb and just run it down the length of the GS, careful not to apply too much pressure and loose the buldges on the bottom '8' string.
Once this is done I use my pin tool. I don't have a picture of it but at best its a wooden handle with a thicker-than-a-sewing-needle pin in it. Use this tool or something like it to press the top layer down into the indentations of the '8' sting by laying the side of the needle completely across perpendicular to the GS string. This creates your top links.
You'll want to make sure that you keep your needle well lubricated while doing this. (this is where you giggle and quote cpt. obvious) so I just dip it right into the bottle and usually keep a bead of FA on it while I'm doing this.
After that I just go back over it and poke little holes where I compressed the top string into the bottom string. It breaks it up and makes it look more like a chain. Also, I'll push the sides in to emphasize the curves of the bottom string.
Lastly, which I did bad in this, very carefully and very very slowly peel up the chain to put it on your model. I use the flat angle, with a bunch of FA, and slowly lift the end while wedging that under it and pulling it off the surface only by the wedging action. Holding the top is just to keep it from curving in on its self.
My chain ended up looking bad in this because I didn't let the GS cure at all before working it and because I didn't take my time pulling it off the work surface.
Here is the chain I made haphazardly wrapped around some spacemarine. Notice hows its stretched out. Thats bad, you don't want your chain to look that way, it looks like garbage. Give it time and be careful when working with green stuff. It should be called GREAT stuff.
Feel free to email with questions!