So I've finally had some non-allocated time and I've used it to research what's new/changed recently. There's a high viscousity, open material jetting 3D printer called NovaJet OPEN now, the Cetus2's near-instant changing, mulitcolour hotend is now on AliExpress for like £100 incl shipping, LulzBot actually came out with a new printer with an approx  28cm * 58cm * 28cm build volume (which I don't know if it's going to survive with a $8K asking price) and I was scrolling through Raise3D's new RMF500 industrial printer website and saw this:

Something I didn't quite realise when thinking of the coaxial capabilities is that abrasion of the nozzle should only happen at the surface of the filament material, and if that material is encased in a non-abrasive material like transparent TPU, hypothetically I could be printing in carbon fibre (CF) and glow filament with a standard brass nozzle. Raise3D also lists poor interlayer bonding as a drawback to composite filaments, adding a bit of credibility to my idea of having the outermost material be a "glue" material.

In other news, the last time I worked on the Coaxial Hotend was November 20th and this is where I left off: