Hi Ben,
In regards to the ZX Spectrum, just a few ideas:
- Instead of making it portable, perhaps you can go a bit more into case-modding, by f.i. illuminating parts of the case or keyboard, or even by making a new case that is fully transparent and illuminated (if that is at all feasible).
- The original circuit-board could prehaps be replaced by a Rasberry-PI running: Chameleon, which includes an emulator called Fuse.
Anyway, thanks for your inspiring videos so far and good luck on your next builds.