"DO IT Yourself: Home Improvement in 20th-Century America," on exhibit at the National Building Museum, is full of historical insights, not the least of which is the recognition of the distinctive American-ness of the can-do spirit. We are, after all, the quintessential DIY nation, a country set up by pioneers with our own built-from-scratch constitution.

Chiefly, though, in its examination of the last hundred years or so, the show zeroes in on World War II as the major turning point in the evolution of the modern uber-handyman/handywoman so familiar from "This Old House" (a television series whose parent company, it should be noted, is a major sponsor of the exhibition and whose clips are prominently featured therein). For it was around and just after the war that certain significant things happened -- the invention of latex paint, for example, along with the rise in plywood's popularity as traditional building materials became more scarce, the streamlining of power tools and the acquisition of manual labor skills by working women -- that turned home improvement into what Time magazine would tout, in its Aug. 2, 1954, cover as "The New Billion Dollar Hobby."

It also boasts several fun and/or informative historical clips from such diverse sources as "Industry on Parade," a National Association of Manufacturers-sponsored TV show of the 1950s that hyped manufacturing capabilities, and Hollywood's version of the fixer-upper's nightmare, the 1990 thriller "Pacific Heights." For kids of all ages, too, there's an impressive array of hands-on interactives, from a treadle-driven scroll saw of the type used in the late 19th century for cutting ornamental woodwork to a mound of brick-size Legos from which you can construct a make-believe barbecue pit. Designed to evoke various parts of a house under reconstruction, "Do It Yourself" also contains a life-size barbecue pit made of real bricks, just one of many nice design touches.

But much, if not most, of "DIY's" sex appeal comes from what, for lack of a better term, I can only call tool porn.

You'll know it when you see it. It's not in the 1920s and 1930s-era commode-and-sink sets on display. It isn't in the vintage ads for paint and linoleum and wallboard -- although they provide a fascinating and at times wry look at how -- and to whom -- home improvement products were originally marketed, starting typically with the exclusively male contractors of yesteryear and ending with the Harriet Homeowners of today. And it's not in the station where you can design your own bathroom tile pattern.

It's in the cases containing old drills, sanders, saws and such. Aside from three power tools that you can touch and a Dewalt radial arm saw that you can't, almost all the tools on view are wisely behind glass. That's where I saw most visitors, the vast majority of whom were men, breathing heavily during a recent visit.

It isn't so much the fact that the tools are pulsing with what Tim Allen's character on "Home Improvement" would have called, in that lewd, caveman voice of his, "more power." Many of them are, in fact, unergonomic relics or woefully out-of-date manual models. And it isn't so much the undeniably phallic nature of many of them. It's just, as things, they embody a history that was -- and still is -- largely masculine, even in a culture where women can be seen comfortably handling a plunger router or refinishing a loft (as two advertisements from the 1980s and 1990s depict).

Do women salivate over tools too? Quite possibly many of them do. It was my wife, after all, who bought a Roto Zip Spiral Saw after seeing a late-night infomercial for one, even though to date she has rarely used it. But, as a 1996 photograph in the show illustrates, the tool aisle at the Home Depot is still primarily, if not exclusively, an overgrown boy's playground.

DO IT YOURSELF: Home Improvement in 20th-Century America -- Through Aug. 10 at the National Building Museum, 401 F St. NW (Metro: Judiciary Square). 202-272-2448.www.nbm.org. Open Monday through Saturday 10 to 5; Sundays 11 to 5. Free.

Advances in building materials -- preformed plywood is touted in this 1951 ad -- helped spur the postwar DIY boom.