Self-assembly denotes a process where individual bricks, such as molecules or colloids, embed the necessary information to spontaneously interact and self-organize into functional superstructures of interest. Operator-free, it advantageously limits errors, intermediate steps and energy consumption, making it a particularly suitable approach for the construction of sustainable and smart materials. Synthetic materials made by self-assembly are usually equilibrium structures resulting from the spatial organization of a repeating single component into a stable structure, such as micelles or colloidal crystals, with a prescribed set of useful properties. They usually have however limited intrinsic reconfigurability and producing desired structures with more than a few different components is still highly challenging. In nature, selfassembled systems are key-elements of living entities and, contrary to their synthetic counterparts, are usually out-of-equilibrium and multicomponent structures capable of dynamic behaviors such as reconfigurability, adaptation or evolution. Obtaining multiple-component self-assembling synthetic materials capable of such life-like functions would arguably expand the applicability, versatility and sustainability of human-made materials. By exploiting the sequence-dependent base pairing principle between synthetic DNA single strands, and compatible with large-scale production, DNA structural nanotechnology appears as a particularly powerful approach to address this challenge, as it allows to program the assembly of hundreds of different components into elaborate superstructures of desired shape, 2,4 size and site-specific functionality, leading to a large scope of applications. The flawless assembly of such multicomponent structures is however usually ensured by a thermal annealing step where the DNA mixture is first heated above its melting temperature before being slowly cooled down to avoid kinetic traps and ensure proper sequence-specific DNA hybridization. Such a thermal treatment hinders any possibility for spontaneous nanostructure formation or evolution under fixed environmental conditions. This also leads to energetically highly stabilized structures for which dynamic actuation and transformation is possible, but typically relies on supplemental action on preformed objects, using for instance linker strand hybridization, strand-displacement, supramolecular interactions, enzymatic editing, or photo-actuation strategies. Thermal annealing thus produces structures that can be actuated once they are formed but that are not intrinsically evolutive. It also constitutes an obstacle to one-pot, in situ functionalization with temperature-sensitive entities such as proteins. From a more fundamental viewpoint, it also raises the question whether such sophisticated, multicomponent DNA nanostructures could self-assemble without mistake at constant temperature. A few isothermal protocols have been described in literature but all having some specific limitations such as involving denaturing agents, preformed assemblies, specific sequence designs or working temperatures. Most of the isothermal approaches were also dedicated to a specific DNA assembly method (e.g. DNA origami or single-stranded tile (SST) assembly), lacking a generic character that could benefit for increased applicability and better understanding of DNA isothermal self-assembly. In this work, we show that the major methods of structural DNA nanotechnology, including DNA origamis, 2 DNA nanogrids and SST assemblies, can now be operated by the same generic isothermal DNA self-assembly principle, leading to a breadth of user-defined elaborate DNA nanostructures that can be spontaneously formed at room or body temperature, keeping intrinsic reconfigurability and a capability of massive transformation never achieved so far. By using a magnesium-free buffer containing NaCl to electrostatically stabilize the forming structures while allowing enough reconfigurability, we established the range of temperatures and salt concentrations where the self-assembly was operational and applied it to the isothermal production of various nanostructure designs and shapes as well as their concomitant functionalization by proteins. By in situ real-time atomic force microscopy (AFM), we revealed the multiplicity of folding pathways in self-assembling origamis. Finally, we performed a series of experiments demonstrating some unique characteristics of this thermodynamically controlled isothermal assembly method, ranging from shape selection in a highly-multicomponent mixture of competing DNA strands to giant shape transformation by the massive exchange of hundreds of different strand components.