Lo-Fi Prototyping
Create the right prototype at the right time.
The purpose of a prototype is to answer or clarify a design question or idea. Thus, a designer’s goal is to answer or clarify that design question in the simplest and fastest manner possible. To achieve this, a designer must build a prototype with just enough fidelity to answer the question, but not so much that resources are wasted. One way to do this is through a lo-fidelity (i.e., lo-fi) prototype, which is built using common, easy-to-access materials and simple techniques. Like any other prototype, lo-fi prototypes can have significant impact on your design, while minimizing resources. In this module, we discuss both common lo-fi prototyping techniques, as well as walk through a few examples that apply these techniques. Though lo-fi prototypes are made more often in the early stages of the design process, lo-fi prototyping is common throughout the design process.
Before you begin…
All prototypes, even lo-fi ones, require some planning before execution. Even a small amount of planning now can save significant time in the future. Therefore, before you begin creating a lo-fi prototype, do the following:
Lo-Fi Prototype Checklist:
- Clearly document the question or idea you are trying to answer.
- your question should be directly related to your client’s requirements and your design specification
- Determine the required minimum fidelity required.
- what features must be included?
- what features can be omitted?
- Determine how you will create your prototype
- what techniques will work well?
- what materials are best suited?
- Define the data you intend to collect and how you will evaluate success and failure
- success and failure should be related directly to your client
Sketching as a lo-fi prototype
Sketching is a very useful skill when designing, serving a variety of purposes. One of those purposes is as a lo-fi prototype. When used in this way, a good sketch can clarify an idea and answer basic questions, and save valuable resources in the process. It’s way easier to create a sketch than to build a detailed CAD model or manufacture a complex part only to discover some very basic aspects of the design. The example below illustrates the use of sketching during the early stages of the design process. To learn basic sketching techniques click the button below.
Designing the front end of a recumbent tricycle.
The sketch and CAD images below were created by a student team designing an independently controlled tilting and turning mechanism for a recumbent tricycle as part of a design competition. Pictured on the left is an early sketch of a potential configuration (i.e., a lo-fi prototype). On the right is a more detailed, resource intensive CAD model that was made to further explore the steering mechanism.
Front-end sketch for a tilting recumbent tricycle.
CAD for the front-end of a tilting recumbent tricycle.
Question:
How are the various steering and tilting components going to fit in 3D space without colliding while still providing the necessary degrees of freedom?
Answer:
Adjusting the width and length of certain components will be key to ensuring there is no interference.
The handlebars must be widened to ensure the seat doesn’t interfere with turning while the trike is tilting.
Prototypes from flat stock and foam
An alternative technique to sketching is to use flat stock or foam core to construct a physical, lo-fi prototype. In mechanical engineering applications, these prototypes often test simple mechanisms or size/space constraints. Flat stock and foam are cheap materials that are easy to cut, easy to join into a variety of shapes, tolerant to mistakes, and easy to stock. The benefit of using such materials is the low monetary investment paired with the ability to create a test model in as little as a few hours. Another benefit is that a designer is able to feel things out as they construct the model, allowing them to modify final dimensions and shapes as they work. The example below illustrates the use of flat stock during the early stages of the design process. To learn some basic techniques for working with flat stock and foam, click the buttons below.
Designing enrichment toys for harbor seals.
The two lo-fi prototypes in the images below were created by a team tasked with designing and building enrichment toys for harbor seals at the Henry Vilas Zoo. The constraints of the project required students to 1) keep costs low, as the zoo is free and has a limited budget, and 2) challenge harbor seals to work for a treat, but ensure the seal’s effort is rewarded. One of the toys the team developed was a floating “fish pusher” in which seals are required to push a paddle through a maze-like channel to unlock a fish treat. The image on the left is an early mockup using cheap and readily accessible materials, including cardboard and a a used plastic bottle. The image on the right shows an advanced iteration of the prototype that uses 3D printed parts (instead of a plastic bottle) and rigid foam (instead of cardboard). This later prototype allowed the team to better understand the final form of the design, but with inexpensive materials.
Early, lo-fi prototype using readily accessible and cheap materials to test an early design idea. This prototype proved the feasibility of the design idea and opened the door to future iterations.
Late, higher fidelity prototype that nearly matches the shape and function of the final prototype. The main difference between this prototype and the final version is the use of cheaper material for this version.
Question:
How well might a channeled tube work as a toy maze that can release a reward when completed? How difficult might this be for harbor seals? Is this the right overall size and shape of container and paddles?
Answer:
The paddle design allows for navigation through the maze, pushing the fish reward towards the top. However it can be difficult to push horizontally with only a vertical paddle.
The maze design can be readily changed, even made more difficult, as the seals learn how the toy functions.
Prototypes from laser cutting and 3D printing
After the initial exploration of a design, during which many early questions were addressed and faults discovered, a designer will often move into slightly higher fidelity prototypes. These prototypes are often solid models, 3D printed parts, laser cut parts, detailed calculations, and simulations. At this stage, designer may create a “looks-like” prototype to communicate a design’s form, or may create an “acts-like” prototype that tests a design’s function. Designers often build many of these prototypes throughout the design processes. The example below illustrates the use of laser cutting and 3D printing to build a lightly more complex prototype to test specific functions of the design. To learn some basic techniques for working with the laser cutter or 3D printers, click the buttons below.
Designing an automated beverage container opener.
The two prototypes in the images below were created by a team tasked with designing and building an automated beverage container opener capable of dealing with both pop tabs and twist off caps of various sizes. Pictured on the left is a solid model the team developed of the container clamping mechanism. The intent of this model was to check for fit and assembly, with the ultimate goal of using the solid models to generate 3D-printed and laser-cut parts. The image on the right was built to verify that the mechanism would work with different diameter cans, to test various materials used for gripping cans, and to explore the implications of teeth size on the ratcheting mechanism. The final design settled on a laser cut base with 3D printed gears and rings, all supported on an 80/20 aluminum extrusion frame.
Solid model for the container clamping mechanism for 3D printing. In addition to generating models for 3D printing, this model helped ensure proper fit and assembly.
The physical prototype built from laser cut parts, 80/20 extrusion, and 3D-printed parts. The container in the clamping mechanism was eventually successfully held and opened.
Various lo-fi printed and laser-cut parts used to build the physical prototype
Final bottom container clamping mechanism mad from 3D-printed parts and mounted to a laser-cut base.
Question
What size teeth and which material work best for the ratcheting mechanism that tightens around the beverage?
Answer:
The relatively low-cost materials and speed of laser-cutting and 3D-printing allowed the team to develop a series of prototypes to test and validate ideas. In the end, the failures and successes of these prototypes helped the designers build stronger/more reinforced areas of various parts, including the ratcheting teeth, and determine the proper material for gripping.
Additional techniques
The above examples are only a few of the possible techniques and materials designers use to create lo-fi prototypes. Additional examples include cardboard, clay, wire, and even Legos. A quick Google search will turn up dozens more. A little bit of creativity can go a long way, and we encourage you to explore.
Fidelity and Prototypes Aren’t Linear.
As stated earlier lo-fi prototypes are often used throughout the design process to test out design ideas and answer design questions. Additionally, because they are quick and cheap, lo-fi prototypes can often be made in parallel with one another, allowing a team to test multiple design ideas at the same time with various goals and levels of fidelity. Prototypes may be iterations on one singular design, or completely different concepts all together.