## 1 Introduction  
Consumer electronic devices have significantly evolved with the Internet of Things (IoT), enabling small devices to be integrated deeply into human activities [1, 2]. Such devices are typically designed for specific purposes, featuring a plastic casing that houses electronics. The devices, like any IoT device, would contain a microcontroller attached to a few sensors and possibly actuators. Industries design most consumer-grade IoT devices to work straight out of the box, with minimal configuration or assembly required. This design approach assumes that the consumer will need to do little more than install the device in the correct location and orient it toward the expected environment or object. Many devices require no calibration and can be installed and switched on. However, many modern devices typically come with built-in intelligent mechanisms that can sense and respond intelligently to their environment. For example, once smart door cameras are installed in the correct location, they can utilize artificial intelligence (AI) to detect targeted human faces and voices specific to their environment.  
While many commercial devices have achieved great success, they also have a considerable impact on the environment and lower flexibility in terms of reusable electronics [3; 4; 5]. A circular economy [6; 7; 8] is a concept that promotes the use of equipment and apparatus that use replenishable materials, and the items themselves can be replenished or reused. Products designed with this principle aim to have a broader range of usage and reconfigurability.  
Consumer electronics are not typically designed with an end-of-life outcome in mind. The majority of electronics devices are manufactured with Acrylonitrile Butadiene Styrene (ABS) plastic, which is difficult to recycle and toxic to the environment [9]. This work aims to explore designing in end-of-life scenarios that matched the perceived usefulness of the personal electronic devices they house [10]. While many materials were considered in this process, drawing a connection between office waste, particularly paper and cardboard, and the ongoing circulation of these materials provided the strongest conceptual link. Furthermore, cardboard offered a range of production alternatives, including a flat-pack approach that is accessible and could involve the user in the making process, a key design strategy to enhance the emotional connection between the user and the electronic device [11]. Using cardboard flat-packs has the additional advantage of being stable, cheap, and recyclable [12]. The key contributions of this paper are:  
1. User involvement in the construction of personal electronic devices. This draws on the Ikea effect of labor equals love and material circularity;
2. Utilizing cardboard flat-packs to encase small electronics to make a consumer-grade product for use in the workplace. This can be used for similar devices in workplaces with less moisture and fire hazards;
3. A calibration mechanism for such devices containing an array of sensors;
4. Additionally, an AI-based classification method for identifying the users captured by the device, which also demonstrates the stability of the new design.  
The remainder of the paper is organized as follows: Section 2 discusses current technologies and the circular economy for producing consumer-grade electronic devices. Section 3 presents the new re-constructible sensor design technique, and Section 4 provides details of the trials and their results. Finally, in Section 5, we discuss the future direction of the proposed sensor design approach.