It seems to me that many of the extrusion based builds use it because there’s no need to be careful to build it square, the extrusion will just make it so.
To be fair, the vast majority of the time, it is. It’s that one time where you tightened a bolt with the corner brace about 1mm out of place, and now nothing on God’s earth is ever going to make that angle 90° ever again short of replacing that length of extrusion and the corner casting, and maybe the other extrusion that it was bolting to. There is (Or was, it might have been junked now) a printer at the local makerspace that’s like that. It’s fine for making vase mode prints, or little knick-knack ornaments, but anyone trying to make (for example) a Primo on that is going to have a bad day putting it together.
So, while I don’t have a problem with Al extrusion, I never want to count on it to make stuff square.
When it comes to tools, (And I count a 3D printer as a tool) I like functional aesthetics. I’m not too concerned about things like colours (though I do pay attention to them) as I am about how they function.
One thing that I’d like to say, is that I’ve had three 3D printers from kits. One used threaded rod, one used laser-cut plywood, and one was extrusion based. I have my self-designed one, and an extrusion based 3018 CNC, and I’ve now built an MP3DP. The MP3DP was far smoother for assembly than ANY of the kits. I remember assembling the base and wondering how I was going to square it up. (I’d cut one of the base floor pieces, which I assumed would do it.) It was perfect. Right from first assembly. Diagonals were right on to within a quarter of a millimeter. None of my kits did that. My self-designed one did, but that was cheating since I made it so that it absolutely had to be, or else it couldn’t bolt together. But I designed it that way because the kits didn’t. Unfortunately I also designed it using cut acrylic which gets a little wobbly, but it’s reinforced with 3/4" aluminum square tube. (I suppose that I could have used 2020 extrusion, but the tube is much cheaper, and worked more than well enough with cheap hardware.)
Ryan’s designs have been a cut above for building all the way through. To build my design 3D printer, I think that I did a pretty good job. I have no real complaints about its performance. I’d absolutely hate trying to make it into a kit. 3mm screws, 4mm screws, 6mm here, 10mm there, 18mm in places, 20mm other places, square nuts here, regular hex nuts there, One-of parts all over the place. Hey, it worked, because I designed for what I had. The kits I’ve bought seem like they were designed that way, too. For what someone had. “Use the 10mm spacers and 18mm screws here, use the 6mm spacers and 12mm screws there. Use 3mm screws for this, 4mm screws for that…” and so on. Often with no discernable reason for or advantage to the unique parts.
So @vicious1 can say that I’m really looking forward to seeing what you come up with here.