Model Prototype Process Blog


For my low-fidelity 3D model prototype, I decided to make the electric screwdriver because I wanted to try to create a handheld object that fit nicely in the user’s hand, and to focus on mechanics like button location and interchangeable screw bits. To begin, I did some research into the OXO brand that was our client for this prototype. Although I was already a fan of OXO for their easy-grip, intuitive kitchen goods, I wanted to dig deeper to understand their design principles and processes. I was inspired by their design philosophy I found on their page:

“Create everyday tools inspired by hands that need extra help, and by helping those hands, you’re helping all hands.” -OXO

I wanted to make my screwdriver easy to hold for every hand size, and easy to operate even with low motor skills or disabilities. This meant I wanted the buttons to be tactile, easy to reach and operate, and clearly labeled. I reviewed the requirements, sketched out my ideas, and came up with my design to prototype.

Electric Screwdriver Sketch

Although the specs suggested that each screwdriver head could be selected automatically, I decided not to implement this for two reasons. First, I wanted my prototype to be realistic, and I didn’t think it would be very feasible to have all the 10 screw bits inside the body and the mechanism to change them. Second, I thought ten different bits would be too many options to tell between without actually seeing the bit itself. So, following the established design standard for current drills and screwdrivers with replaceable bits, I decided to make each bit manually replaceable and magnetic to attach to the body. To adhere to OXO’s design principles, I wanted to make each screw bit easy-grip so that you wouldn’t have to grab the small, slippery metal tip to change it. Next, I prototyped my idea.


I played around with materials for a while to best understand how I could use them to achieve what I wanted to create. I decided to use foam core to create a solid interior of the screwdriver, and then cover it with modeling clay to smoothly shape an easy-to-hold handle. I then added foam buttons and a paper screen on top of the clay and wrote labels for each. I made the screw bits out of foam, nail files, and sticky magnet sheets.

The screwdriver turned out larger than I expected because the clay added some length to the foam core interior. The magnets were also weaker than I expected, so the screw bits fell out with a shake. With the limitations of my low-fidelity prototype in mind, I went on to user testing.


Through user testing with a few tasks and an in-class peer critique, I was able to find the strengths and weaknesses of my design.

What worked well:

  • The shape of the handle was “comfortable to hold” and “ergonomic” for users with many different hand sizes
  • The functions were easily discoverable, especially with the clear labels
  • The buttons and switches were consistent and clear
  • The power button was easy to reach with one hand
  • The long handle actually turned out to be “great for large hands”

What needed improvement:

  • The placement of the switches were a bit too high, users said they were worried about hitting them accidentally
  • The buttons fell off because of weak tape, a limitation of my prototype
  • One user mentioned that the handle might be too big to use in tight places
  • The numbers on the screen were not clear to one user as to what they meant
  • One touch power button is not standard, a trigger was more expected

In conclusion, my electric screwdriver design was effective in that it met all the requirements (other than automatic screw bit selection) and was intuitive, easy to use, and comfortable to hold for many hand sizes. However, there are also many improvements I would like to make before another iteration, such as the switch placement, or implement a press and hold power switch.

Short clip from my user testing:



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Sarina Katznelson

Sarina Katznelson

User Experience Designer, always putting the user first.