Traditional Cajun triangles are made by bending a cast-iron tine of an old broken hay rake (the kind that horses pulled) into a triangle shape, with curled edges. They are usually bigger and thicker than the triangles that are often found in the percussion section of orchestras and concert bands, and therefore have a deeper, richer tone.
The Cajun triangle is played by holding the triangle in one's fist, and clamping and releasing the instrument itself, while simultaneously striking the triangle with an iron beater (usually made of the same material, in the same thickness). The clamping and releasing action gives the triangle a bit of tonality, and allows the player to control the ringing. In a waltz beat, the standard playing method is [clamp, open, open, clamp, open, open] and for a two-step, it's [clamp, open, clamp, open]. In both cases, the triangle is struck twice during each clamp and twice during each open. To achieve proper rhythm and tonality on the triangle is no small feat - it's deceptively difficult.