Harps are traditionally wooden instruments, and the majority of harps today are still made with a wooden frame and soundbox. However, there are some harps out there that use alternative materials in their construction, from fibreglass to cardboard to plastic. One person even made a harp all out of PVC tubing! However these harps are much less common and usually custom made.

Popular woods used in the construction of the frame and soundbox include walnut, maple, cherry, ash, and some more expensive or exotic woods such as mahogany, purple heart and bubinga.
The most common wood for the soudboards of harps is spruce, with Sitka spruce ranking quite high in terms of its reputation for being a good soundboard wood. Some soundboards, for instance in lower-cost harps, may be made out of less expensive materials such as plywood or birch laminate.
If you're concerned about the growing world-wide problem of unsustainable wood harvesting, or the harvesting of endangered or rare species, be sure to check with your harpmaker to see what source(s) he or she uses, and try to support companies that use sustainable forestry practices if possible. At least with a harp, the wood is being used to craft a valuable musical instrument that can potentially be around for generations, as opposed to going to make disposable items or other wasteful or unnecessary products.

Strings are usually made of either nylon, gut (or synthetic gut), wire, or a combination thereof. Celtic (folk, lever) harps are most often strung with nylon or wire; classical (pedal) harps are usually a combination of nylon (high end), gut or synthetic gut (mid-range), and wire-wound (bass). Many of the bigger folk harps (34 & 36-string) also have metal-wound strings in the bass octave. Wire-strung harps at one point almost vanished altogether, however they've made quite a resurgence recently, and now many harp companies offer wire-strung models along with their nylon-strung models. Historically, some harps (esp. in Wales) were strung with horse hair, however this appears to be an obsolete practice, although you may find the occasional replica harp strung with hair; it apparently gave the harps a quiet, buzzy sound.

For more information on historical harps and how they were built, check out some of the links on the historical links page, or pick up one of the books on harp history listed in our Harp Books section.

If any harp-makers or historians out there feel they have anything to add to this section, please feel free to email me with the info; it would be great if you could include your sources, too.