Sounds like similar resin/filler mix as would be used for epoxy granite CNC machines, remember years ago reading about cast (in situ) concrete bass horns,think yours are probably going to look a bit prettier...

You`re a lot different from the Russ Andrew`s corner of the audio market ,genuinely trying out new methods and materials, remember to cryo treat the binding posts though :-)

Remember your trials with Strike originally , to see you turning out stuff like this now helps spur some of us on who feel they were getting a bit stuck, really inspirational., though personally unlikely to be making high end epoxy granite speakers any time soon

Can add a second vote for a quick video about aligning parts.

Thanks