A pair of bodies can be made of three or four layers of fabric. I prefer the latter: Two layers of "basis" between which the boning is sandwiched, one layer of top fabric and one of lining. In case of the three-layer version, the boning can live between the basis and the top fabric or between the basis and the lining, so that the boning may either show on the outside or chafe on the inside. Mind you, this doesn't have to happen, but if the fabric isn't thick enough, it's a distinct possibility. The four-layer variety is also the one that can be easily and quickly mocked up and worn for a while simply by leaving off the top and lining layer for the time being.
The basis should be stiff and strong, non-elastic, and breathe well. Anything that is stiff and strong enough for jeans is suitable. Cotton is OK, but linen is the only authentic choice.
As for the top fabric, wool, linen and silk can be used, either solid or with a woven pattern. The softer the top fabric is, the greater is the risk of the top fabric warping. That's no problem if (any only if) the top fabric is relatively dull. Shiny fabrics such as satin should, therefore, be reserved for fully-boned stays, and even then you should stay away from something as slinky as crêpe satin. For lining, linen is the most authentic, but cotton works as well.
The rule of thumb for fabric consumption is: 50x150 cm per layer. I.e. 100x150 for the basis on account of it being double.
Which kind of boning is best suited depends on the size and on whether it's half or fully boned. Since we're looking at half-boned here, I roughly estimate 8-11 metres of 1x10 mm plastic boning for a slim to normal figure. Proper plastic boning behaves much like baleen in terms of stiffness and elasticity. There's an extra page about the choice of boning for the non-standard figure. Stay away from rigilene and spiral steels! They all are way too weak for our purposes.
If you'd rather use authentic boning material, the only choices are reed or cane or a kind of wood that is nott too flexible and doesn't break easily. I've been told that ash works well. Depending on the kind and size of the reed or wood, it can replace plastic. I have not used it, so you'll have to experiment. It's probably fine for small to medium sizes. On the other hand, each of these materials breaks more easily than real whalebone would have done, and most of the time you'd have to prepare (i.e. split lengthwise, remove splinters etc.) the stuff yourself. If you have the means to do so, you're welcome to try it.
To neaten the edges you'll need 5-7 metres of tape or ribbon, depending on the size and number of the tabs (that's the rounded flaps along the lower edge). Bias-cut tape is most suitable because it is easier to bend it round the tabs. Do not use readymade cotton bias tape from the shop, though: It is too stiff and too wide. Bending tape around the upper end of the tab slits is awful work even with narrower and soft material. It's better to use the top fabric or some other not-too-thick fabric and cut it into 3 cm wide strips. Fold 5 mm on each side towards the middle and iron. Another alternative is taffeta ribbon or leather (see chapter 5). As for the colour: It should of course go well with the top fabric, i.e. the same colour or a complimenting one.
For authentic stays, linen thread must be used. Otherwise, normal sewing thread is fine. For the lacing eyelets, buttonhole silk or linen thread. Reckon 8-10 metres for one lacing or twice as much for front-and-back lacing. Metal grommets are not suitable: They were not used before ca. 1830. Busks like this one were not used, either.
As for the lacing, I personally prefer 3-5 mm wide satin ribbon because it goes through the holes smoothly. Moreover, it is available in a number of colours, so it is relatively easy to match it up with the binding tape. It is easily strong enough. Normal cords are also fine. You'll need about 5-6 metres for back-lacing only, plus 2 metres in case of additional front lacing.
For cutting plastic boning any strong scissors are suitable - just don't use the best and sharpest ones you have. You can also cut a deep groove with a sharp knife, then bend the bone until it breaks right along the groove. Cut off the corners to prevent them from working themselves through the fabric. If the boning is inserted between two layers of strong base fabric, and the tunnel ends closed off with strong seams, it is not necessary to file the ends round. For steel boning, plate or wire cutters are best suited. In this case, the ends have to be blunted. Filing is usually made awkward by the plastic coating, so it is better to buy end caps along with the boning. Other alternatives are tipping fluid (if you can't get that, thick lacquer) and sticky tape that you wrap around the ends. The tipping fluid (lacquer) has the added benefit of protecting the ends from rust. Mind that this makes the bone ends thicker, so the tunnels have to slightly wider.
For marking the tunnels you should use pens that give exact, narrow lines. Since the tunnels are not visible from the outside, all sorts of pencils, ball-point pens or whatever can be used. Just make sure that the colour doesn't bleed through the top fabric if it gets wet.
Chapter 2: The pattern