For more than 40 years, Richard Tuttle has preserved and developed a unique voice in the art world, a sensibility that balances opposites. He can seem at once incredibly precious and completely nonchalant; deeply invested in his project and lightheaded about it. Works are simultaneously exquisitely crafted and belligerently flimsy. Materials are throwaway stuff, scrapings and waste, but treated lovingly. His current show at Sperone Westwater performs a similar feat of sustained ambivalence, with works that are adorable and prickly in equal measure.

He has hit upon a new format that he calls “extensions.” There are five groups of these, labeled Section I through V, identified by where they were made (New York, New Mexico) with varying numbers of individual pieces. Each extension consists of a hard to categorize work, painted and shaped, generally around 3 inches or 4 inches in width and height. Within each series, this element is consistently flat or in the round — more like drawing in one series, that is to say, or sculpture in the next. Each piece is mounted on a similar bracket, the thin edge of a cross of two bits of balsa wood affixed to the wall on the other thin edge by a strip of hammered aluminum armature wire. The bracket has the same Tuttle-esque ambiguity of weight as the work it carries: pragmatic and fey in equal degrees. While functional, it is also — according to the artist — symbolic, in theosophical terms that recall Mondrian, of the meeting of immanence and transcendence.

“Section I (New York)” is the largest grouping, with 21 extensions lettered A-U. It is also the most planographic in that the supported element is itself a support, a flat piece of stiff, Fabriano watercolor paper. “Section I: Extension G” (all works 2007) is one of the more straightforwardly painterly pieces. The pictorial part is around 4 inches by 3 inches, and figures a letter “I” shape, or I-beam, in bright red against a loosely watercolored background in light and dark blue. This “I” lives a double life: It could read as the letter, or as a structural shape indifferent to its signifying function.

This ambivalence is typical of Mr. Tuttle: While essentially an abstract artist, he frequently deploys a pictorial vocabulary of characters, letters, or glyphs: “R”s and “T”s are favorites in the current show, putting you in mind of Robert Ryman’s playful signature. And there are often elements that hover on the brink between inchoate shape and recognizable or nameable symbol, a practice in harmony with the dichotomy in his work between hard and soft intentions (purposiveness and aimlessness) and a use-it-or-lose-it ambivalence toward language.

This is a beautifully installed exhibition that places each series in a separate room, hung at an even pace and at the same level. The use of letters to denote the extensions has an effect of making the viewer think of alphabets: that each of these works has a unique character, but that they fall into place within a bigger scheme. There is at once a sense of self-containment and variation on a theme.

For as many pieces that form recognizable or potential signs or glyphs – the figure 6 spiral of “Extension K,” for instance, or the protruding ocher diamond shape, made of two conjoined boomerang shapes, standing proud of the white square support, in “Extension D” — there are shapes and activities that don’t submit in this way. “Extension F” has two “doors,” watercolored ocher with a red horizontal stripe at its center, with a serrated edge, that open on a colored pencil composition behind. “Extension M” is similarly layered: A lattice front repeats a shape painted on the paper behind. Occasionally, the artist lets his hair down, so to speak, with recognizable representation. “Extension R” is a flower, the ends of its five petals dipped in a different color, against a ground quartered in different colors.

Section II, which has five extensions, replaces paper with wood as the extension’s support medium. It is in Section III, a series of 13 extensions made in New Mexico, that the extensions make the leap from flat supported image to fully in the round sculptural object, though the series retains the split between organic shapes and glyphic signs. “Extension D” is a blue “T,” for instance, garlanded by a cream-colored coil. In this series, the medium of the extensions is for the most part aluminum foil, giving the work its sculptural freedom. It is an irony typical of Mr. Tuttle that a flat paper should create a volumetric form.

Back in New York, Section IV, a series of 12 extensions, sees the introduction of transparency as an active component. “Extension D” is an open lozenge cutout of wood colored in metallic paint, with a pill-like shape protruding at one point. “Extension C” has four Q-tips (or elements like them) against a matteboard ground that is white below, black above, reading somewhat like piano keys. More than before, you begin to notice the shadow play in this series. “Extension F” has just a thin blue strip protruding, but the shadow play it generates creates much pictorial incident.

“Section V,” the last group, also made in New York, introduces the greatest variety of materials. Plastic literalizes the issue of transparency, as a see-through support. Hot glue is a favored material throughout the show. Like the burr that results from his rough cuts into cheap wood, the little glue globules result from function, but at the service of another element they become an element themselves. In “Section V, Extension A” a thin spread cake of hot glue become the support, the affixed pigments serving as much as texture as color.

The beauty of Mr. Tuttle’s art is that you do not have to take on trust that, for instance, his cruciform bracket symbolizes transcendence and immanence, because this is a mystical aspiration that permeates all his aesthetic choices. Crappy things are rich treats; clumsy actions produce delicate results. In a tour de force of reconciled opposites, the show is guided throughout by rigor and whimsy.

Until June 30 (415 W. 13th St., between Washington and Greenwich streets, 212-999-7337).