The shell almost invariably has a circular opening over which the drumhead is stretched, but the shape of the remainder of the shell varies widely. In the western musical tradition, the most usual shape is a cylinder, although timpani, for example, use bowl-shaped shells.[1] Other shapes include a frame design (tar, Bodhrán), truncated cones (bongo drums, Ashiko), goblet shaped (djembe), and joined truncated cones (talking drum).

Drums with cylindrical shells can be open at one end (as is the case with timbales), or can have two drum heads, one head on each end. Single-headed drums typically consist of a skin stretched over an enclosed space, or over one of the ends of a hollow vessel. Drums with two heads covering both ends of a cylindrical shell often have a small hole somewhat halfway between the two heads; the shell forms a resonating chamber for the resulting sound. Exceptions include the African slit drum, also known as a log drum as it is made from a hollowed-out tree trunk, and the Caribbean steel drum, made from a metal barrel. Drums with two heads can also have a set of wires, called snares, held across the bottom head, top head, or both heads, hence the name snare drum.[1] On some drums with two heads, a hole or bass reflex port may be cut or installed onto one head, as with some 2010s era bass drums in rock music.

On modern band and orchestral drums, the drumhead is placed over the opening of the drum, which in turn is held onto the shell by a "counterhoop" (or "rim"), which is then held by means of a number of tuning screws called "tension rods" that screw into lugs placed evenly around the circumference. The head's tension can be adjusted by loosening or tightening the rods. Many such drums have six to ten tension rods. The sound of a drum depends on many variables—including shape, shell size and thickness, shell materials, counterhoop material, drumhead material, drumhead tension, drum position, location, and striking velocity and angle.[1]

Prior to the invention of tension rods, drum skins were attached and tuned by rope systems—as on the Djembe—or pegs and ropes such as on Ewe Drums. These methods are rarely used today, though sometimes appear on regimental marching band snare drums.[1] The head of a talking drum, for example, can be temporarily tightened by squeezing the ropes that connect the top and bottom heads. Similarly, the tabla is tuned by hammering a disc held in place around the drum by ropes stretching from the top to bottom head. Orchestral timpani can be quickly tuned to precise pitches by using a foot pedal.