Tamper-respondent assemblies and methods of fabrication are provided which include an enclosure, an in-situ-formed tamper-detect sensor, and one or more flexible tamper-detect sensors. The enclosure encloses, at least in part, one or more electronic components to be protected, and the in-situ-formed tamper-detect sensor is formed in place over an inner surface of the enclosure. The flexible tamper-detect sensor(s) is disposed over the in-situ-formed tamper-detect sensor, such that the in-situ-formed tamper-detect sensor is between the inner surface of the enclosure and the flexible tamper-detect sensor(s). Together the in-situ-formed tamper-detect sensor and flexible tamper-detect sensor(s) facilitate defining, at least in part, a secure volume about the one or more electronic components.