The requirements of the programme evolved from a second home first, to a guesthouse and finally to a hotel. The site is a plot of land in the foothills of Mount Meru, facing Kilimanjaro and with a panoramic view of the Maasai steppe. The entire development was to be self-sufficient in each phase due to the lack of services in the area. The project is based on three strategies, concerning energy, water and materials. Regarding materials, bamboo and compacted soil blocks were used instead of the more common materials in the region, which are timber and cement blocks. Bamboo was used for the main structure of the buildings open to the public: the bungalows and a common area (Figure 1).

These main structures support the roof of the aforementioned buildings and consist of six flat triangulated modules composed of beams, columns and struts. The six modules are arranged radially, generating a dome with a hexagonal base, articulated at the apex as a reciprocal structure (Figure 2). As there was no bamboo for construction in the Tanzanian market at the time, the whole industrial process related to its harvest and treatment to obtain a high quality building material was put into practice on site. Training sessions were held for local craftsmen and workers to learn how to build with bamboo.

The client requested the extension of the main building of a hotel complex located next to the road leading to the Mayan site of Palenque, in the state of Chiapas, Mexico. In this case, the area already had treated material ready to be used in construction, as well as craftsmen experienced in bamboo construction. The result is a gallery parallel to the existing building (Figure 3), created by seven flat modules. Each one of the modules is conceived as a truss whose beam extends beyond the support furthest from the façade of the existing building, generating a cantilever which free span is shortened by means of an inclined strut. This generates a three-dimensional structural framework which, in addition to optimising its operation and resistant sections, generates an organic lay out that turns the supports into tree-like structures (Figure 4).

These are types of support widely used in the history of architecture with different materials, not only to shorten the span of cantilever elements but also to group and channel the resulting loads, as in the case of Gaudí's Sagrada Familia [6] , the famous Palazzeto in Rome by Pier Luigi Nervi [7,] Terminal 4 at Madrid airport by Richard Rogers and Antonio Lamela [8], or Stansted Airport by Norman Foster [9].

In 2017, a 'tensegrity' structure [10] was designed, calculated and built for a circus company planning to perform a show on it. Its final height was 8 metres, achieved by using nine bamboo culms compressed by steel cables (Figure 5). The bamboo culms were joined in groups of three, each group generating two tetrahedrons linked by a vertex. These groups were connected horizontally, on the ground, using the steel cables. Once all the cables had been tensioned, the assembly, being a rigid structural unit in itself, was lifted with the help of a crane and placed vertically in its final location (Figure 6).

In October 2019, a three-day intensive course on bamboo construction took place at the Universidad Politécnica de Madrid, aimed at students and professionals. The theoretical part of the course was held at the Escuela Técnica Superior de Arquitectura, while the practical part aimed at the execution of a greenhouse to remain in the experimental agronomic fields of the Ciudad Universitaria - Moncloa campus (Figure 7).

The design concept behind the experimental greenhouse is based on three-dimensional, self-supporting structural modules (Figure 8). A sequence of three of these modules was arranged one after the other and covered with polycarbonate panels previously fixed to flat bamboo modules as gables (Figure 9).

Greenpeace Spain, inspired by and activism action developed in the UK and knowing the previous experience of the studio in Mallorca, requested in autumn 2020 a similar vertical structure for one of its actions. However, due to the requirements of this case, the modular system is radically different: it must be transported in a small vehicle such as a van, and it must be able to be assembled without auxiliary means (such as scaffolding or cranes) in a maximum time of 15 minutes (Figure 10).

The system consists of three equal elements, made up of culms hinged together at their ends [11]. Each of these elements can be extended lengthwise or folded in the shape of a W or M. When these three elements, which in isolation could be considered flat (or even linear, if they are extended lengthwise), are linked together, they manage to remain in equilibrium, the whole being a three dimensional element (Figure 11). This assembly is deployed vertically in sections, up to a total of three, each of these sections being fixed by means of the triangulation carried out with steel cables, exceeding 6 meters in height when the device is fully deployed (Figure 12).

In order to achieve a design that could be easily assembled and disassembled, 'bamboopod' was conceived, a system that has been fully developed and patented by the studio. The main reasons for the application of this design concept are to reduce the impact of logistics on the selling costs of bamboo structures, to optimize resources (due to the controlled working environment in the production plant) and to increase accuracy, which is reflected in the quality of the final products (Figure 13).

The aim of this technology is to turn bamboo into a common, even mainstream, building material. The strategy for this is to develop products in which bamboo plays a key role, combining it selectively with other materials and adapting it to work together with commercially available building systems. Used as culms, not as boards or laths, bamboo is a material that can even have a positive environmental impact, given its carbon dioxide sequestration performance and the low energy consumption required for processing [12]. The design is driven by the concepts of added value, prefabrication, mass-serial production, zero-waste manufacturing, and a quality working environment. These are all existing concepts. However, bringing them all together in a harmonious way in relation to bamboo construction is an unprecedented approach. The main material of the system is bamboo in its natural form [13], but it is combined with iron fittings, PET and PVC fabric, and eventually an aluminium frame cladding system such as windbreaks or curtain walls. In this way, all materials used in the system are biodegradable (bamboo), reusable (iron) or recyclable (fabric, and aluminium), and therefore zero-waste manufacturing can be achieved (Figure 14).

Only what is to be built arrives at the construction site, where no more than two people with spanners and ladders are needed to erect a given structure. Once dismantled, it is packed in a compact form, i.e., a 7 by 7 metre module, which reaches 4 meters at the highest point, and its roof, takes only 3 by 3 by 1 meter room. This reduces transport costs, both in economic and environmental terms. The system is designed to be easily assembled and disassembled by following the instructions manual, making it suitable for both permanent and temporary uses. The heaviest component of the system weighs 20kg, thus any of them can be handled by one person. All components are packed in boxes of less than 50kg, to be carried by two people. Power tools are only used on the production plant, which increases safety.

The commission received was a room for practices and group therapies, with a drop-shaped appearance from the outside, based on the concept of a rhombohedral dome and with bamboo laths as the structural material of choice. The roof is made of reused ship's sail fabric (Figure 15).

The required surface area made it evident that structural ribs were necessary for the structure to be safe and sound. Therefore, the building is a drop-shaped tent with a hexagonal plan whose structure is based on polygonal arches. Each segment of the arches is made of bamboo laths arranged in parallel and tied with cable ties, inspired by the traditional Japanese weapon called 'shinai'. The project is conceived as a set of pieces that users shall assemble following a manual, which is organized in three parts (Figure 16).

The first part is the drawings of the finished construction. The second part is the steps to follow for the assembly and erection of the prefabricated parts. And the third part contains the instructions and drawings for the fabrication of these parts, which have limited dimensions to minimize transport costs. Therefore, when the construction is disassembled, it also needs very little room to be stored. Due to the hexagonal plan, six half-arches rise from each corner of the room and join at the top, first creating a six-pointed star and also forming the base for a cupuline, in order to achieve the intended drop shape of the structure (Figure 17).

To stabilize and give structural unity, a series of horizontal rings are installed to link the vertices of the polygonal arches that are at equal heights. The structure is finished with the incorporation of shorter elements, in the form of triangulation between the rings, to prevent them from buckling (Figure 18).