Hybrid Exhibition Design (HED) involves physical environments and digital layers (e.g. AR/VR, IoT, and web3D), introducing multidisciplinary complexity across curatorial, design, and technological domains. To address the need for flexible, scalable, and accessible Authoring Tools (AT) in this context, we propose a methodological framework based on layered abstraction (components, widgets, templates), aiming to streamline collaborative design and rapid prototyping. Applying this methodology within the ATON framework, we developed ''Prototyper'', a web-based 3D authoring platform that enables non-developers to design, configure, and simulate hybrid museum experiences. The Prototyper Minimum Viable Product (MVP) implements minimal but expandable features, including 3D model integration, semantic interaction mapping, spatial measurements, and viewpoint simulation within a widget-based architecture. Developed as a proof of concept within the H2IOSC Project, this work demonstrates the feasibility of empowering co-design processes, reducing technical bottlenecks, and supporting more iterative, multidisciplinary approaches to exhibition planning in Cultural Heritage (CH) contexts.