Abstract: Disclosed herein are viewing kits that can be assembled and coupled to visual content sources, such as e-readers, to facilitate viewing visual content. Example viewing kits include a viewing aid, which may include a light, lens, filter, or other implement, and an interchangeable fastener that can be removably coupled to the viewing aid using a slot-and-key interface or other suitable coupling mechanism. Either the fastener alone, or the fastener coupled together with the viewing aid, provides a deformable cavity that is shaped to clamp onto an edge of the e-reader. Inserting the e-reader into the cavity causes the fastener, which is made of resilient material, to bend outwards. In response, the fastener exerts a pinching force on the e-reader, creating a pressure fit that connects the viewing aid securely to the e-reader.