Vocational education and training (VET) is the most popular form of upper-secondary education in Switzerland, with more than two-thirds of the teenagers enrolling in a VET program after finishing their compulsory education. The vast majority of the Swiss VET systems have a dual-track structure where students learn in schools for one or two days per week while they do an apprenticeship in a company for the remaining days. Their professional competencies are developed through a combination of workplace experiences reinforced by the theoretical knowledge learned in school. While the apprenticeship at workplaces provides valuable experience to the learners, one concern is that there is a lack of diversity in the experiences of an individual apprentice. Motivated by this limited experience of VET learners in the workplace, the goal of our research has been to explore the possibilities of expanding their experiences. Focusing on design-related professions in VET, we consider exploring digital variations of a design as a way to expand the original experience related to the design. The research objectives of this thesis are (1) exploring possibilities to expand the experience of learners in design-related VET and (2) investigating the potential benefits of the expanded experience. To accomplish the research objectives, we formalize the idea of expanding experience for VET learners by defining the three dimensions of expansion: parametric, temporal, and social. We explore these three dimensions in three studies. For the parametric dimension, we investigate how learners explore a multidimensional space of possible designs using a digital tool and how we can support the process with an interface that enables disentangled exploration of design parameters. We present a tool called BloomGraph that has been developed for florist apprentices to explore flower bouquet designs, and the results from an experimental study that investigates the effectiveness of a graph interface for design exploration. For the temporal dimension, we explore how we can support the VET learners with envisioning the designs that change over time. We present a virtual-reality tool called GardenVR developed for gardener apprentices that allows creating a garden and exploring it in an immersive environment. In an experimental study with gardener apprentices, we investigate how they explore the time dimension using the tool, compare the tool with the current method of practice, paper-sketching, and study how the two interfaces can be combined in an instructional design to enhance the design outcome. Lastly, for the social dimension, we present a tool called Mixplorer that has been designed for a classroom scenario of gardener apprentices. The tool provides a way to socially explore design spaces by allowing the apprentices to create an initial design and recombine it with the designs of other learners. We present the results of two studies conducted using the tool that investigate its feasibility in the VET setting, potential benefits for the learners, and the effectiveness of the design-mixing process in creative practices.