In recent years, additive manufacturing (AM), also known as 3D printing, has emerged as a uniquely powerful tool for rapid prototyping and for creating complex, high value structures. Vat polymerization (VP) is an AM technique which forms parts through light-initiated polymerization, capable of achieving both high resolution and high throughput. While VP has been utilized to fabricate a wide variety of polymeric materials, fabricating functional materials such as ceramics, metals, and inorganic composites has remained a challenge. This thesis focuses on developing fabrication methods for a range of functional materials, from battery active materials to metals and ceramics, via vat polymerization additive manufacturing, taking advantage of chemical reactions within an AM part after fabrication to form target materials in situ. We demonstrate the use of emulsions to introduce aqueous active material precursors into organic photopolymer resins to create architected lithium sulfide/carbon composites for use as lithium-sulfur battery cathodes. Such architected cathode materials are promising for mitigating mechanical degradation in high volume-change battery materials such as the sulfur cathode. We additionally performed nanome- chanical experiments on lithium sulfide powders to determine how lithium sulfide yields, deforms, and fails in the context of volume-change-induced stress during battery cycling. Because lithium sulfide is present as a discharge product in all lithium sulfur batteries, these nanomechanical particle compressions have bearing on the entire field, beyond the realm of 3D architected cathodes. We additionally demonstrate the use of organogel templates to streamline the AM process by enabling the fabrication of many materials starting with a single resin composition, followed by infiltration of appropriate metal precursors and post-processing heat treatment to convert the polymer/precursor matrix to the target metal via calcination and reduction reactions. We fabricate and characterize copper, nickel, silver, cobalt, cupronickel alloys, tungsten, and more to highlight the wide-ranging versatility of achievable materials and microstructures.