Multi-material 3D printing is the key to fabricating innovative components across diverse fields, including biomedical, automotive/aerospace, and electronics.1 Especially electronics can benefit since it can support recycling by producing easily dismantlable compounds, highlighting its potential for sustainable manufacturing. Therefore, the "Design for Disassembly" concept has already been employed in the creation of such components through multi-material 3D printing in vat photopolymerization.2 However, when two dissimilar materials are used, the adhesion of the interface layers is crucial to the (thermo)mechanical properties of the component.2 The binding properties at the interface of the materials, whether created via covalent bonds or entanglements, are determined by the functional groups present in their respective formulations. The entanglements can result from an interpenetrating polymer network (IPN) state, which is formed through the intermingling of the two formulations during the printing process. Covalent bonds can only form if both formulations contain functional groups that can polymerise with each other. Here we introduce a (meth)acrylate-system as material A, an allyl-thiol system as material B, and an acrylate-thiol system as material C, with the objective of examining the interface of 3D-printed components on a microscopic scale. The findings of the (thermo)mechanical tests of the multi-material compounds are compared directly to those of the single-material prints. The process under discussion facilitates the comparison of theoretical reachable and measured properties. Moreover, the intermingling of the two materials at the interface was tracked via SEM imaging and EDX measurements, with two commercially available photoinitiators being investigated for this purpose.