Advancements in radiation detection for robotic deployments are described concerning the use of low-density, multifunctional, metal-foam materials as collimators. The use of nichrome (NiCr) metal foam, poly(methyl methacrylate) (PMMA) foam with stainless steel powder, and 3D-printed tungsten foam experimentally to isolate radioactive isotopes in constrained environments has been explored. This research demonstrates that these materials used in this way might reduce the payload associated with heavy metal collimators significantly relative to conventional, homogeneous alternatives such as solid lead and tungsten, and hence that they might enable spatial characterisation tasks that would otherwise be infeasible due to payload constraints—particularly in robotic systems where the use of conventional high-Z, dense collimators can limit their flexibility. The results suggest that metal foams and related materials can make collimation-aided localisation viable in such constrained settings, offering advantages in mass and characterisation granularity.