;Sound Box designs • The
antiguo design: This box resembles a medieval keyhole, also known as cuatro cuadrao, or cuatro araña. This shape has been found on some old dotars and citolas. Four-string, eight-string and ten-string cuatros were made using this design. This was the very first design and it might be 400 years old. Sometimes some ten-string cuatros are still made with this design. • The
aviolinado design: This box resembles a violin. It is the most common shape used today. Eight-string and ten-string cuatros were made using this design starting in the 19th century. • The
dos puntos design: This box looked like some old mandolinas made by Martin in the United States during the 20th century. However, it was first used in the 19th century in
Yauco, Puerto Rico. Eight-string cuatros were made using this design. • The
tulipán design: This box looked like the antiguo design but with no straight lines and all curves and thus resembled a tulip. Eight-string and ten-string cuatros were made using this design during the 1900s near Yauco and
Ponce. • The
higuera design: This is the rarest design. This box was shaped like an organic oval. This was because the soundboxes were made from domed gourds instead of wood. Four-string cuatros were made using this design in the 19th century in Puerto Rico by enslaved
Africans on the island. Now they are made with ten metal strings and often have designs carved onto their backs. • Besides these, many other lesser-known and one-of-a-kind designs also exist. ;Variants In the 1950s, there was an effort to produce a "classical" ensemble of cuatros, with various-sized instruments taking on the role of the violins, violas, cellos, and double basses in a classical orchestra. To meet these roles cuatros of the aviolinado style were produced in four different sizes and tunings:
Cuatro Soprano,
Cuatro Alto,
Cuatro Tradicional (the standard instrument, also called
Cuatro Tenor), and
Cuatro Bajo (Bass Cuatro): all have ten strings and are tuned in fourths. The project met with only limited success and today most of these variants are rare, with the
cuatro tradicional surviving as the standard instrument. There is also a
Cuatro Lírico ("lyrical cuatro"), which is about the size of the Tenor, but has a deep jelly-bean shaped body; a
Cuatro Sonero, which has fifteen strings in five courses of three strings each; and a
Seis, which is a Cuatro Tradicional with an added two string course (usually a lower course tuned to F-Sharp in Octaves), giving it a total of twelve strings in six courses so it can also be used as a 12 string Parlor Guitar for Traveling. ==Cuatro orchestras of Puerto Rico==