Preface: I do understand and sympathise with this topic although being a bit unease at details.
Is there an established name for this field? ‘DIY computing’
There is a very classy (well, classic) term for this: homebrew
Is ‘DIY retrocomputing’ in scope, and to what extent?
Obviously Raspberry Pi or Arduino would be out of scope
This is already where it gets blurry.
Think of Oscar's very fine KIM UNO. Hardware wise it's nothing else than an I/O 'shield' for an Arduino Pro Mini (Atmega328P)
For this and similar systems (like the PiDPs - again by Oscar Vermeulen), I would suggest going the same way as with emulations: If the issue at question is something that would as well occur with the real hardware, then it's clearly on topic, as the different hardware is gets cancelled out.
but how about new retro-based designs like CX16?
Rather not. I guess you made already a good point with
"...re-creations of old hardware or new designs made from old parts.."
For faithful re-creations of classic system I'd say yes without any doubt. I, for one, only recently learned that there is a new (!!!) Triton board. It doesn't happen often that I get really excited about recreations, but that one really got me involved :)) It only replaced the 1k by 1 RAMs with still available 1k by 4 and a few secondary components (like ROMs). Beside that it's as original as it can get. Awesome and I'd be all in favour to accept questions about the - after all, these will be exactly the same topics the original systems would have had.
A creation with classic components should be treated like a homebrew machine from back then. My preferred example here is the Steckschwein. It is a complete new design not direct following any example (well, the memory part is screwed C64 style), combining a 6502 with MMC and 9958 based graphics. So again, while new, I would accept questions about such systems, as the issues are exactly the same.
Developments like the RC2014 series might, at times, be borderline, but falls into the same category.
Modern clones and near-clones?
This is were machines like CX16 or Spectrum Next come in. I have a hard time to see them still as classic systems, as they are on hardware level thruout modern systems. A FPGA loaded with some CPU code that can execute (among other) classic Z80 instructions is maybe a lot, but not a Z80 and even less a classic CPU. They rather offer some kind of hardware assisted emulation and should be treated like emulations. Questions about host system or emulation interna must be off topic.
Given, Spectrum Next et.al. carry some of the classic spirit, but so do Small-BASIC users on Windows 11, while at the same time any modern system based on an AVR or alike is in hardware terms more classic than these modern developments.
Where should the line between computing and electronics be drawn?
Like so often it can only be judged by intend and target. If it's about basic electronics on itself (like asking how to calculate a resistor for some network), then it should be off topic and go elsewhere. If it's about the same resistor network in context of a specific (classic) computer, then it's of course on-topic as it is about that computer.
Now for the tags:
clone is a very distinct term that is quite needed with classic machines as well. Not only for the fact that IBM-PC clones had such an impact, but as well for all the cloning that happened early on.
- An IMSAI is an Altair clone
- Lobo or Genie are Tandy clones
- Laser 2001 and MPF-II are close Apple II clones
- SYM and AIM are in some ways KIM clones
- ... and so on.
It seems that
clone is needed whenever a question is about such machines and their relation to the prime version.
diy-computing on the other hand seem not only redundant but random as well. In addition they may be less easy understood by non native speakers. Similar
homemade. To me a common tag
seems more appropriate. This tag can be used for old and new machines as well.
To mark new(ish) developments, I'd suggest a tag
re-creation). Or even better:
which would mark it without any doubt.