Material tinkering and developing the GIY kit

Seven organic substrates were tested: coffee residue, overripe banana, sawdust, oat, carob, horse chestnut ground and rice to examine how substrate composition influences growth rate, surface formation and structural integrity after drying (Figure 1). Five microscopic fungal species were selected for their potential to yield visual and textural distinctions on material outcomes: Trichoderma asperelloides, known for its characteristic green pigmentation; Laetisaria arvalis, which produces orange tonalities; Alternaria alternata, with pigmented or dark-colored mycelium, generally appearing gray, greenish, dark olivaceous, dark blackish-brown, or black; Macrophomina phaseolina, with dark brown to black mycelium covering the surface; and Monilinia laxa, which forms flower-like or patterned growth structures (Karaca and Karaca Reference Karaca and Karaca2023; Lawrence et al. Reference Lawrence, Rotondo and Gannibal2016; Martini and Mari Reference Martini, Mari and Bautista-Baños2014; Siddiquee Reference Siddiquee and Siddiquee2017). These species are less frequently utilized in design-oriented biomaterial research, which typically favors macro-fungi such as oyster mushrooms (Pleurotus ostreatus) or Ganoderma species for their rapid colonization and ease of cultivation. The deliberate inclusion of these unconventional species aimed to investigate alternative material potentials emerging from their distinct biological behaviors, particularly the formation of sclerotia, dense structural forms, in certain species.

Figure 1.

Substrates used in the fungi cultivation process.

Substrates were sterilized by autoclaving and inoculated with fungal spores under controlled laboratory conditions (25°C incubation). The preparation of the samples is shown in Figure 2: preparing substrates by mixing with a sucrose-water mixture, autoclaving for sterilization and inoculating the fungi spores on the prepared substrate media. After the active growth phase, samples were dried in an oven at 50°C for 24 hours. This dehydration process resulted in dimensional shrinkage and increased structural rigidity. The applied temperature was sufficient to inactivate fungal spores, rendering the materials non-living and safe for direct handling within the workshop setting. Across all species-substrate combinations, the tinkering process documented variations in growth rate, surface pattern formation, pigmentation, binding capacity and post-drying rigidity.

Figure 2.

Preparation stages of fungal material tinkering: substrate preparation (left), sterilization by autoclaving (center) and inoculation under controlled laboratory conditions (right).

Observations were recorded both during active growth (Figure 3) and after drying stages (Figure 4) to compare structural stability and visual/sensory attributes.

Figure 3.

Active growth stage of fungal materials.

Figure 4.

Post-drying fungal material samples.

In addition to these microscopic species, a commercially available oyster mushroom (Pleurotus ostreatus) strain, commonly used in home mushroom cultivation kits, was included for comparative purposes. Microscopic species required laboratory inoculation and sterile preparation of substrates. The oyster mushroom strain was provided in pre-inoculated substrate mixtures and was tested under non-sterile conditions to evaluate handling and shaping feasibility. This strain was provided in a pre-inoculated compost block within a small container, accompanied by instructions for users to mix it with additional substrates, such as used coffee grounds, which were presented during the workshop as an example, to experiment with material formation.

Material tinkering with BC was conducted using a commercially available home kombucha kit. A pre-formed SCOBY pellet was cultivated in sweetened black tea at room temperature. To introduce variation, different sugar concentrations and fermentation durations were tested, with results showing that both variables influenced the thickness and density of the resulting cellulose pellicle. Rose hip tea was used as an alternative nutrient base to examine chromatic differences in the produced material. After harvesting, pellicles were subjected to three drying conditions: air drying, oven drying at 140°C and oven drying at 200°C, each producing distinct differences in shrinkage, surface texture and final material stiffness. Fermentation was also conducted in containers of varying size and geometry, revealing that the pellicle conforms precisely to the surface area and shape of its container, a finding with direct implications for mold-based shaping within the GIY kit.

Carrageenan, a polysaccharide derived from seaweed and widely used for its gel-forming properties (Lopez Rodriguez Reference Lopez Rodriguez2023), was selected for algae-based material exploration. A formulation of 5 g/L of carrageenan was prepared and heated until fully dissolved. While still in liquid form, the mixture was poured into molds of varying size and geometry; upon cooling, the material solidified and retained the shape of the container (Figure 5). Variations in mold geometry produced differences in thickness distribution and edge definition. Additional shaping experiments involved extruding the heated mixture directly into ice water, producing filament-like strands that demonstrated the material’s capacity for form variation without the use of rigid molds. Natural colorants, including turmeric, were used to test color variations.

Figure 5.

Algae material samples.

The GIY kit was structured around three organism-related material categories: algae-derived carrageenan, kombucha-derived bacterial cellulose and fungi-based mycelium materials, which were selected to create experiential variation within a single kit while remaining feasible to prepare outside of a laboratory setting. Each kit contained a small portion of carrageenan powder for algae-based material shaping, a small jar of kombucha SCOBY (symbiotic culture of bacteria and yeast) for BC cultivation, a small jar containing a pre-inoculated oyster mushroom strain grown on corn substrate and a selection of microscopic fungal specimens for observation of growth variation.

Grow it yourself kit and tinkering workshop

The GIY kits developed through the iterative tinkering process are shown in Figure 6. Each kit was prepared to enable hands-on engagement with all three material categories within a single workshop session. 18 senior industrial design students attended the workshop (pre-workshop survey N = 18; post-workshop survey N = 17) and participated in hands-on tinkering. Of the 17 post-survey respondents, 14 directly handled algae, 11 handled BC and 10 handled mycelium; two participants indicated they observed but did not directly engage with the materials (Figure 7).

Figure 6.

Grow It Yourself Kits.

Figure 7.

Students working with materials.

During the workshop students played with the BC, pulling it to break and feeling the texture making them comment about its strength. Most of the students prefer to use gloves while interacting with it, showing discomfort about its texture and the smell.

Pre-workshop surveys revealed that 15 of 18 participants were encountering biofabricated materials for the first time; two had engaged briefly through a class or personal experiment and one had attended a dedicated course or workshop. Prior material familiarity was low overall, with self-rated familiarity scores (1–5) averaging 1.72. Regarding kit experience, eight participants had no prior experience with any GIY or DIY kit, while the remaining ten had worked with plant-growing kits (N = 6), craft kits such as ceramics and soap (N = 7), food fermentation kits (N = 3), educational or science kits (N = 3), or material experimentation kits (N = 2). Notably, five participants reported having had hands-on experience with algae-based materials in some form before, two had with BC and three had worked with mycelium.

The most commonly stated expectations for the session were “hands-on material experimentation” and “learning about biofabricated materials” (each cited by 13 of 18 participants), followed by “exploring sustainability-related materials” (N = 9), “creative exploration without a defined outcome” (n = 6) and “gaining technical knowledge” (n = 4).

Analysis of post-workshop survey responses, combining structured attribute ratings with qualitative open-ended reflections, revealed distinct sensory profiles across the materials in the GIY kit (Figure 8). Across the post-workshop responses, tactile and sensory descriptors were frequently used to characterize the materials. Algae-derived carrageenan was the most positively received material across all sensory dimensions. The most frequently attributed descriptors were “fragile” and “transparent”, followed by “smooth,” “flexible,” “gel-like,” and “pleasant to touch”. “No noticeable smell” was also noted for algae, the only material for which odor absence was a widely reported positive quality. Qualitative comments reflected this positive tone: one participant described algae as feeling “like a transparent membrane,” another noted it “was way easier to work with than I imagined,” and a third likened it to “slinky” material reminiscent of fish skin and nature. Several were struck by its plastic-like optical qualities, with one participant observing that “plastic-like materials can also be produced in different ways.” BC from kombucha presented the most complex perceptual profile. It was overwhelmingly associated with “noticeable smell”, “uncomfortable to touch” and “smooth,” “soft,” and “flexible”. Qualitative descriptions were as following: one participant described the BC as “like chicken breast skin,” another said it felt “slimy and disgusting,” and a third noted it “reminded me of touching a human.” Surprisingly, a handful of participants reported BC as “pleasant to touch” and one remarked that “kombucha was really hard to break”, an unexpected structural quality also stated by another, who described it as “nearly unbreakable with brute force.” Mycelium-based fungal material was marked above all by its visual and sensory characteristics. It was most frequently described as “organic-looking”, “opaque”, “uncomfortable to touch” and “noticeable smell”. Structural terms such as “hard”, “fibrous”, “rough”, “brittle” and “unstable” further characterize it as a dry, crumbling, organically textured material. Yet some participants reacted positively, describing mycelium as “pleasant to touch,” and one evoked a naturalistic metaphor, noting that “the green fungi looked a bit like moss and wood.”

Figure 8.

Tactile and Sensory Qualities by Material.

Smell emerged as the dominant challenge across all three organisms. Among the 14 participants who described a specific challenge in open-ended responses, the majority cited smell or a combination of smell and texture. Representative responses included “survive the smell,” “tolerate the smell,” and “the smell and overcoming the textures.” A smaller number cited visual aversion (“the way they look and the feeling of not wanting to touch it”) or conceptual unfamiliarity (“getting to know them and seeing how they react to different organic materials”).

Participants’ attributions of material behavior revealed a consistent set of meaning-related categories shown in Figure 9. Across all three organisms, “natural” was the most frequently selected behavioral descriptor, “Growing” ranked second for both fungi and BC and fifth for algae. The attribution of “unique” was strong across all three. “Unpredictable” was particularly prominent for fungi and BC, whereas algae were more frequently described as ‘predictable’ and ‘familiar,’ receiving the highest familiarity rating among the three materials. “Living” was most prominently attributed to BC while “intelligent” was most frequently assigned to fungi. Qualitative reflections supported these attributions: one participant noted that working with the organisms “felt like touching nature.” Post-workshop reflection questions asking participants about values communicable through biofabricated materials yielded a strikingly homogeneous response. “Sustainability” was selected by 16 of 17 respondents, the nearly universal value across all biomaterials and engagement styles. “Experimentation” was cited by 15 of 17, making it the second most prevalent value.

Figure 9.

Material Behavior Attributes by Material.

Post-workshop design concepts showed how participants referred to material qualities when developing design rationales. Participants’ self-rated scores for the extent to which materials influenced their thinking about form, function, or use (1–5 scale) averaged 3.06. The majority of scores fell at 3 or above (11 of 17), with five participants rating the influence at 4 or 5. Aesthetic pleasantness was rated at a mean of 2.65, suggesting a moderate overall aesthetic response that varied considerably between materials.

13 of 17 participants submitted a design concept. Algae was featured in ideas such as dissolvable food packaging (“food packaging can be made with algae instead of using plastic wraps”), a children’s motor development play kit leveraging algae’s pliable, gel-like properties, a food dressing application exploring its edible potential and translucent lighting, interior space dividers for parks or homes exploiting its optical clarity. Notably, two-thirds of the concepts involving algae-based materials specifically emphasized translucency as a defining material quality. The Dissolvable Spice Pods concept (Figure 10) reimagined single-use plastic/paper food packaging with a sealed seasoning pod made entirely from edible algae bioplastic; the participant’s material reflection noted: “I chose algae because of its solubility and food-safe properties. Instead of designing a package that needs to be torn and thrown away, the material’s properties allowed me to design a package that becomes part of the meal itself.” Another participant proposed translucent interior space dividers benefiting from algae’s translucency, reasoning as follows “because algae is translucent, I think you can convey the emotion and feeling you want to give to users very well by using algae panels.”

Figure 10.

Student design concept Dissolvable Spice Pods.

Although BC was often described unfavorably in sensory terms, several BC-related submissions engaged closely with specific material qualities such as tensile strength, translucency, skin-like texture and temporal transformation. One participant developed BioNet (Figure 11), a hybrid concept combining BC due to its tensile strength with algae due to its cleaner look: “I chose to combine it with algae because algae samples felt cleaner, lacked the strong odor of kombucha, and were much faster to produce. I decided to use this hybrid approach to merge the strength of one material with the cleanliness and speed of the other to solve a real-world environmental problem.” Two concept submissions treated BC at a more aesthetic and conceptual level. The Veil concept positioned BC as a “living membrane” to be suspended in space, exploiting its translucency, skin-like surface and sensitivity to light rather than any functional application saying: “the material’s organic irregularities added depth without disrupting the overall purity of the concept” and that “replacing it with an artificial material would compromise the softness, depth, and aesthetic authenticity of the design.” The Growth Table concept proposed BC as a living tabletop surface that “grows, dries, and transforms over time,” treating thickness variations and imperfections from the growth process not as defects but as “evidence of growth and interaction” and framing maintenance as part of ownership, engaging with the livingness of the material as a design value.

Figure 11.

Student design concept BioNet.

Concepts generated with mycelium were fewer and the material properties that inform the concepts were due to it being hard, fibrous, brittle and organic-looking. One participant proposed temporary biodegradable acoustic sound panels for concert and event venues (The Node, Figure 12), directly motivated by mycelium’s sound-absorbing property: “the aim is to produce temporary stands or use them as sound panels in concert or event venues. The material traps sound, naturally preventing sound propagation in open spaces. This reduces the amount of plastic waste generated after use in such events and creates biodegradable organic waste.”

Figure 12.

Student design concept The Node.

Kit accessibility scores averaged 3.88 out of 5, indicating that participants generally found the GIY kit accessible as a design exploration tool. In terms of perceived kit structure, 9 of 17 respondents characterized the kit as one that “encouraged open-ended experimentation,” 5 described it as offering a “balance of guidance and freedom,” and 3 found it “mostly prescriptive or step-based.” When asked what would need to change to better support design exploration, participants most frequently requested printed instructions, illustrated guides, or step-by-step booklets to enable independent replication at home. Representative suggestions included “a small booklet with images describing the process,” “a trial booklet so users could replicate experiments outside the workshop setting,” and “an information card with images describing the products and their processes.” One noted the need for physical forming aids such as flexible molds or frame structures.

The likelihood of experimenting with biofabricated materials in future design projects averaged 2.71 out of 5. One participant rated re-engagement at 5 while describing the workshop as “an engaging event because it was a topic that sparked curiosity.” Another, despite noting that the smell was challenging, reflected that “I will try to do more experiments in the future” and that she had previously assumed a laboratory was necessary for such experiments. A third stated they were “now more curious about creating different materials and thinking about sustainability more.” Conversely, some participants who struggled with all three materials rated future likelihood at 1 or 2, with one stating, “I don’t think these materials are going to be used to make any object or product,” although product examples were shown during the workshop lecture and throughout the course.