top of page


just a wonderful solution

Final Design

How it works 

The final tool design is meant to be used for opening and closing drink packages with twist caps. When the two handles of the tool are closed together the teeth of the clamping mechanism will also be closed together. This means that when someone wants to use the device to open a cap, they will first have to move the two handles apart. Then an opening will appear in the middle part of the tool to fit around the bottle cap.

Placing the bottle cap inside the teeth of the device will have to be done using a combination of sight and feel. The final concept based on concept 4 now has 5 teeth instead of 3, because this will help to steer the cap into the middle of the tool if the participant has not placed the middle of the tool properly on top of the twist cap. After this the handles can be squeezed towards each other, making the teeth of the tool guide the cap to the middle of the device and clamp around it. When the participant feels the resistance of the teeth on the twist cap, the participant can pull the rubber band to lock the clamping mechanism around the twist cap. Then with a wrench-like motion, the participant can remove the twist cap of the bottle. Because of the system, the user requires less force and coordination to open the cap. 


Because the twist cap is left clamped inside the tool, it can also be used to twist the cap back onto the packaging when someone is done pouring a drink. This is done by placing the tool with the cap still inside it, back on the drink packaging. And by using the device as a wrench, the bottle can be closed. To be able to use the device for a different bottle, the user has to pull the handles apart again, which requires a bit more force since it also loosens the locking mechanism. 

tool with bottleee.png

Clamp the twist cap by squeezing the handles

tool final.png

Application to the user


The current design and size of the cap-opener are fully adjusted to the specific measurements and needs of the participant and their symptoms of Ataxia. With some small modifications in the sizing of the tool, especially the size of the handles. A universally applicable tool could easily be realized, which will be helpful for more people running into the same struggles with opening and closing twist-caps. 


A universal handle size should be based on known physical ergonomics of an average adult hand with an average length of 18cm and an average width of 8,4cm. The handle should still be slightly oversized and remain a similar shape, making it easier to hold on to for people with less fine motor control. 

These minor adjustments make the tool useful for people with Ataxia, conditions with similar symptoms, but also for all other people who could use some extra force or grip when opening a twist cap packaging


In order to improve the design and make it even more useful, several components could be looked into and developed further. 

One of these elements is aiming for the twist cap with the tool. In the original design, this has to be mainly done by feeling if the lid fits in between the teeth of the device. This action could be improved in several ways such as by using a clear material in the tool which makes it visible if someone is aiming right or by a slanted edge on the teeth which guides the lid to the right place. Also, increasing the number of teeth that can push the lid to the middle could be useful and another option would be to include a light or laser on the roof of the device which can then shine down on the cap to guide you to the middle of the tool. 


Another major improvement would be an internal mechanism that can clamp a lid automatically or without much effort. As of right now, in order to clamp the tool around the lid, an external elastic/ rope has to be tightened. This could cause problems since it would require the user to both keep the tool in place, while also fastening the handles. A solution for this would be a mechanism that will fasten automatically when the handles are squeezed together. 

One more way of improving the product is to make it universally useful for not only small twist caps on drinks but for any kind of packaging with a twisting cap such as a jar or a toothpaste lid. This could be solved by making the tool also usable on even larger caps, or to make several different tools in various sizes. 

tool with bottleee.png

Mechanism explanation

Model mechanism.png

The mechanism of the product consists of 5 “teeth” that concentrically close around the bottle cap. While the image on the left is not the final concept, it clearly shows how the mechanism works.


The black part are the teeth that clamp around the bottle cap.


The light gray and dark gray parts are the two guide slots that allow the teeth to move closer together when the two handles are squeezed together.

Style collage 

Our co-designer really likes Apple products,  owing to their sleek design and ease of use. Since the particpant owns several Apple products, the participant would prefer to have a product in the same style. We created a style collage based on his preferences (image 1). Based on this, we will tailor the design to his personal preferences.

bottom of page