In the olden days, women's magazines used to drag out their mix 'n' match feature every time the seasons changed. The idea went something like this: with only five pieces of clothing -- a skirt, pants, two blouses and a jacket, say -- you could have 150 different outfits for any time of the day or night. Add a scarf and the numbers multiplied exponentially.

That same idea, more or less, can be applied to the stockpot.

Stock is something that appeals more during the colder seasons, although some cooks find it indispensable all year round. But in warmer months, there is still a need for big pots, and this is where you get to mix and match. What to cook the corn in? All four of your little household saucepans is not the right answer. What to steam the lobster in? What to cook the spaghetti for 25 in? The three dozen crabs?

But first, the stockpot as stockpot. Making stock is the kind of activity that seems daffy and irrelevant until you've done it a couple of times and reaped the rewards. Then being out of stock feels like being out of milk.

Veal stock, made from meaty veal bones and flavorful vegetables, sounds a little la de da, and it is. Veal stock is the reason all those sauve, exquisitely expensive little sauces served in fancy restaurants taste so good. If you have veal stock on hand -- and it freezes perfectly in covered Styrofoam cups -- you can turn pan drippings from any meat into your own suave sauces simply by adding good veal stock to the pan and letting it reduce and thicken.

So let's say you're going to try stock making and need a pot -- a big pot -- to do it in. (There's no point in making a little bit of stock, and those bones are big.) What you need is a pot taller than it is wide, so that the flavors can blend slowly over a period of several hours with as little evaporation of liquid as possible. This is not the same animal as a soup pot, which will be wider and shorter.

When you go to shop for your stockpot there will be four choices of materials: regular aluminum, anodyzed aluminum (like Calphalon), copper and stainless steel. Buy copper if you have a couple of hundred dollars you don't know what to do with and think of your pots as art. Buy anodyzed aluminum for more or less the same reasons, although these will be somewhat cheaper and somewhat less like art. It's not that they're bad for making stock, just slightly overbred.

That leaves stainless and plain aluminum. Most professionals use plain aluminum, sometimes in sizes so big that they have a spigot at the bottom for emptying. The arguments against plain aluminum for a home stockpot center mainly around appearances. Aluminum discolors and eventually gets pitted when it comes in contact with acidic foods, and it never looks pristine again once it's been used.

A more serious criticism concerns its reputation for affecting the flavor of acidic foods cooked in it. I've never found this to be a problem with my aluminum stockpots, and I've used them often for steaming seafood in wine, then used the resulting stock to make a sauce. If the stock is to be greatly reduced I usually transfer it to another pot, but mainly because a stockpot is too big to make a little sauce in.

If you find these things worrysome, buy a stainless steel stockpot, a species that's increasingly rare these days. Vollrath, an American company, had a corner on the stainless stockpot market until it stopped making its pots available to the retail trade last fall. And, retailers say, there is not yet a good substitute on the horizon.

But if you hurry there are still a few Vollrath stockpots floating around town in retail stores, and they can also be ordered through restaurant supply and equipment houses. The advantages? They can always be kept sparkling clean, won't stain, and will never exchange odors or flavors with the food that's cooked in them.

But before you run out and buy a stockpot, think a minute about size. A stockpot is not really a stockpot until it gets to be 8 quarts or bigger. A 20-quart pot, which is really the smallest size most restaurants would bother with, will hold at least four lobsters and probably five or six. But it is about 11 inches high, and may not fit on your stove top if you have an overhead oven. The usual domestic burner may not be a match for it, either.

Most home cooks should probably think about a 10- to 16-quart pot, although if you entertain with crab feasts or lobster boils, the bigger the better. Measure your facilities before investing and watch for sales this time of year.

But we're not through with mixing and matching yet. By adding a steaming rack, these big pots become perfect for steaming vegetables, too. Asparagus fits nicely in them, as do whole heads of cauliflower or quantities of potatoes.

Some aluminum pots -- usually the thinner gauge, cheaper ones -- come with separate, perforated-aluminum inserts designed just for holding the food to be steamed. But if what you're interested in is a larger, sturdier basic pot, buy a steamer rack or one of the little flower-like, adjustable-size steamers. The flower-like steamer is preferable because it will be easier to pull out of the boiling water.