This thesis on SPP is long, but worth a read as it contains information on spherical layered resonators of a special construction which coincidentally, we have seen before:
COHERENT PLASMON COUPLING IN SPHERICAL METALLODIELECTRIC MULTILAYER NANORESONATORS by Rohde https://scholarsbank.uoregon.edu/xmlui/bitstream/handle/1794/8592/Rohde_Char les_Alan_Phd_U08.pdf?sequence=1 It can imply the way that Patterson's CETI beads "could have worked", and possibly why the later beads failed to work. The tolerances are most important in connection with a light source. This thesis, of course, does not mention CETI, LENR or Patterson, but it does talk about how to get SPP coherence in structures which are similar to JP's beads - using layering of conductors and dielectrics. The problem could have been simply lack of quality control in attaining proper thickness coatings, but also . even with proper quality control, a gainful cell would have benefited greatly from a dedicated monochromatic light source - tailored to the thickness of the layers. SPP was essentially unknown technology at the time, and this assumes that SPP were involved which is not proved. Some coincidences are really just that - purely random.
