The ceramic avenue has shown some promise, we know a project group in DARPA was following the tantalum hafnium carbide trail as late as 2013, but the compound cannot hold a sufficiently fine edge longer than a few minutes, and oxidizes at 430° C, meaning it likely cannot be field-activated without him detecting it, barring a complete.
The research material supplier Goodfellow USA produces the compound as a 45 µm powder, at a price of which is agreeable to budget, but there is concern that this is not a high enough purity to avoid Mattis’ Material-Adaptive Defense Protocols (MADp). The NSA’s opinion as of March of 2019 is that he can reliably detect the pressure fluctuation upon hermetic sealing, but we don’t know of any follow-up to that report.