Alida Ratteray
Engineering & Design
NURSERY REDESIGN
Mechanical Design Case Study
In the DFM phase of the Farmshelf launch, I was tasked with redesigning the nursery for manufacturability, cost reduction, technical requirements, and usability. The nursery is a critical subassembly of the Farmshelf unit, where seedlings spend the first weeks of their grow cycle under highly controlled conditions. The nursery prototype used for preliminary plant testing was designed to establish and validate optimal environmental conditions for plant growth. However, the prototype was not designed for scaled manufacturing and had significant cost and usability concerns.
Prototype nursery, closed drawer.
Prototype nursery, open drawer.
KEY DESIGN CONCERNS
MANUFACTURING & COST
The original nursery enclosure used machined ABS panels and hardware, making it costly for scaled production. It featured a pull-out drawer for the three grow basins, with the humidification system mounted inside the drawer. This design required expensive components like drawer slides and a drag chain for sliding electrical connections.
TECHNICAL REQUIREMENTS & SAFETY
Cables ran below the grow basins to connect to electrical components mounted on the pull-out drawer, creating electrical hazards in the event of leaks. The crevices of the drawer slides increased unwanted biological growth, creating a cleaning nightmare for users.
USABILITY
It was critical that any design changes still allow for an easy and enjoyable user experience in planting, watering, harvesting, and cleaning. While the drawer design allowed for easy access to the basins, the excessive number of components posed cleaning challenges for users.
DESIGN REFINEMENT
Alongside the Industrial Design team, I developed an updated nursery design with a focus on eliminating costly components and safety hazards while improving the user experience in planting, watering, harvesting, and cleaning.
IDEATION
I held brainstorming sessions with the Industrial Design team, sketching ideas and aligning on design requirements.
PROTOTYPING
I used rapid prototyping tools such as 3D printing and laser cutting to test variations of the grow basin handle design, ensuring ergonomic and intuitive design.
USER TESTING
I conducted interactive testing sessions, observing how users intuitively used the updated design, collecting feedback, and identifying design risks.
MATERIALS AND MANUFACTURING RESEARCH
Costs and production lead time were primary concerns. I investigated three manufacturing routes for the nursery enclosure: 1. sheet metal; 2. injection molding or thermoforming; and 3. a combination of sheet metal and plastic. After ruling out sheetmetal due to thermal requirements, I compared injection molding and thermoforming, assessing options for reducing upfront manufacturing costs due to tight budget constraints. I ultimately proposed an injection molded enclosure, allowing for precise molded-in mounting features, molded-in rails for the grow basins, smooth seams to mitigate microbial growth, and reduced cost of parts and assembly.
DESIGN FOR MANUFACTURING
Pre-DFM DESIGN
Machined ABS walls assembled with hardware—high manufacturing and assembly costs
Pull-out drawer design includes drawer slides and drag chain, adding significant cost
Cables running through splash zone below basins, creating electrical hazard
Numerous off-the-shelf components mounted to enclosure, adding cost, complexity, and cleaning difficulty
Post-DFM DESIGN
Injection molded ABS enclosure
Hinged door eliminates drawer slides and drag chain
All wiring immediately routed to outside of enclosure, protected from humidity/water damage risk
Molded-in features eliminate several components from Bill of Materials, including fan covers, vents, and mounting hardware
FINAL DESIGN
SIMPLIFIED, SAFE DESIGN
Modified from the original pull-out drawer design, a hinged door houses the humidification system, redirecting all cables from the splash zone at the nursery base. The simplified design meets all electrical and food safety requirements.
SIGNIFICANT COST-DOWN
The hinged door design and use of molded-in features eliminate several components from the Bill of Materials, including the drawer slides and drag chain, significantly reducing costs.
INTUITIVE USER EXPERIENCE
The grow basins are rotated 90 degrees, seated in slots built into the base of the nursery. Users are able to slide the basins out just enough to add water, limiting the saplings’ exposure to the outside environment. Additionally, the elimination of components improves ease of cleaning for the user.
Mechanical Design at Farmshelf
In the DFM phase of the Farmshelf launch, I was tasked with redesigning the nursery for manufacturability, cost reduction, technical requirements, and usability. The nursery is a critical subassembly of the Farmshelf unit, where seedlings spend the first weeks of their grow cycle under highly controlled conditions. The nursery prototype used for preliminary plant testing was designed to establish and validate optimal environmental conditions for plant growth. However, the prototype was not designed for scaled manufacturing and had significant cost and usability concerns.
Mechanical Design at Farmshelf
I specialized in consumer-focused components that significantly improved the user experience in cleaning, harvesting, and refilling units. A key challenge was adapting my design process to be both user-centered and plant-centered, balancing ease of use with the strict biological needs of the plants. Cleanability was critical for plant health, as reducing contamination directly improved growth.
One example was the water level dams I designed for the grow shelves. These components had to be easy to remove and replace without getting lost during cleaning, while meeting strict mechanical and material requirements for a watertight seal and NSF food safety standards. I designed a unique over-molded gasket design to guarantee a reliable seal in case of tolerance issues, and the removable design cut cleaning time by 80%, ensuring customer and plant success.