Two cents from a guy who hasn’t built squat: My initial plan was to build a 25.4 MPCNC and then a LR2. So I started printing my parts. Actually I bought a printer, then started printing.
The intent to build both was the reason I bought an Ender 3, thinking that after subtracting material costs, it would be a wash vs buying the parts, but that’s another rabbit hole to go down…
As I got 90% of the way printed, I started working on other material costs, the shop next door does nothing but stainless, so we started working up costs for the MPCNC. I was shocked at the cost of material for this little beast, and began to contemplate (and start printing) parts for the LR2, as most of the purchased parts were interchangeable, and 25.4 ss would be much cheaper on the larger machine.
I calculated that it would indeed be cheaper to reprint the MPCNC for conduit, and since committing to a LR2, not stretch the size too much, keep it nice and small and accurate.
And then Ryan drops a new version, another reason to wait!.
The point of this long winded dissertation is the thought that yes the price difference between conduit and stainless might be enough to put somebody off of making one, or push them to a maslow or a Chinese built small format machine.
So yes, even though it must be a PITA to make parts for 3 and perhaps 4 or 5 (1.25", 1.5"), it’s the bottom end guys that get hooked on something cheap. Look at me, I had no intention of buying a 3d printer 6 months ago, much less building either machine. And yet now I’m hooked.
As I said, just 2 cents from a guy who’s done nothing but buy filament.
I would be surprised if these were not designed as parametric parts, in which case its mostly just changing a parameter and re-exporting the models. I say mostly because care must be used in designing them, and there is only a certain range of parameters that can be reasonably used, and its always good to have someone test each version to make sure that 0.4 mm difference doesn’t make a wall too thin, or a flexible part too stiff.
SS is a lot more expensive than EMT (easily 10x more!) but allowing/supporting/recommending your design to be used with cheap materials can reflect on the perceived quality of your creation. There isn’t a right answer here; but its not as simple as it seems.
It IS a good point though. I think there are a lot of people looking for something…cheap… to get into. For me, I wanted a low cost way to supplement my 3d printer for a car project. None of you would be surprised to learn how much I’ve actually spent now, lol, but I’m not either. It’s the INITIAL hurdle to get involved and find out if this is the right technology for one’s needs.
Over the last year, I’ve gathered that Ryan is happy with three outcomes: user builds and enjoys machine, user builds and enjoys machine so much that user builds more of them, user builds machine and learns so much that user feels compelled to buy/build an actual commercial production - level cnc.
I think between the engineering, the part simplicity, the entry cost, and the capabilities of these cncs, it’s really tough to beat for entry - level tinkerers. And part of owning those guys is cheap parts.
From previous comments in previous posts, I would be surprised. I think Ryan would like to have it parameterized, but there are too many places where things have to be tweaked just so to handle the other parts (bolts, bearings, etc), that it’s not as simple as we’d like to think.
Only to elitest snobs who are chasing 0’s they don’t need anyway… 
And the people who listen to them… 
IIRC, a “reasonable” build has an error that is still measured in the hundredths of an inch. And it’s repeatable. In my mind, and at certain times, V1 and the MPCNC is a big ole fat middle finger to the “traditional” CNC world. There’s a gear-head in the back of my skull screaming at me about spindles and linear bearings and all sorts of crap that, frankly, I don’t need. And I’ll never need. If I ever get to the point that I do need them, I’ll hopefully be in a position to drop the really big bucks I’d need to to get a high-end, industrial CNC machine. But I’m building a hobby machine to toy with. To make little things around the house, maybe some gifts. So I don’t need 0.0001" precision, and I don’t expect it. If I can get to the point that I can do v-carve inlays with minimal gaps, I’ll be thrilled!
DOM is significantly less expensive than SS. I understand you want to build a machine that can use the same size rails, but that is not the design intent. If you want the lowest cost CNC possible go spend $8 on EMT (not $120 on SS) as designed and have a ton of fun and learn a lot. Then if you want something huge, buy DOM or SS for a LR.
For either machine the steppers and electronics will cross over, but the rails never will completely different size. So build a EMT MPCNC, and start learning.
I see what you are trying to do, but by making than one assumption you turn a $380 kit into a $500 kit. Still by the way far from any other machine by about half even at the SS (delivered) price.
They are not. It just gets too complicated on an intricate machine like this.
Having seen the history, and my informal sampling of the users (sorry, users, you’ve been sampled). There is a real “bimodal” shape to our user pool. Of course, things aren’t only one dimension, but we get a lot of users who are interested in making a machine that acts like a jobsite table saw, saving as much money as they can, but busting open doors that were previously reserved for the elite workshops.
Then there are the types that want to squeak out as much value as possible, and try to spend an extra $100 to gain an extra $300 in competitive performance. The first few revs of the MPCNC were trying to go as low as possible, and weren’t interested in eeking any more performance than necessary to do the minimum build, in a small space, to prove that you don’t have to spend $2000 on an “entry level” CNC machine. Then people realized that it is just about there to be able to go bigger, faster, more materials, and we are (of course) tinkerers, adjusters, changers, and occasionally improvers. 1" Tube (SS or DOM), Dual endstops, Burly versions, Low Rider, Rambo, these are all improvements that come from trying to get more value (overall performance or performance per dollar).
But the fundamental equation is that having the cheapest machine available enables more people to be able to enter the arena. That’s a core niche. It is what dragged me in. I have the money to buy a $2000 machine, but I never would have. I just know I won’t get that much value out of it. I jumped in at <$400 (and I reused some things, and had a printer, so probably closer to $250). I never would have done that at $1500. There are quite a few users like that here. And some that have used it to develop a (cost sensitive) business.
We are learning more and more. We are finding new ways to bring features from the “high value” group into the “lowest cost” group. We need (and want) both groups to move forward. If we find that DOM or some ikea shower rod is going to be a better solution for the low cost group, then you can bet Ryan won’t make a conduit version in the future. Until then, expect to still see the “lowest cost” and “high value” groups supported.
And, FWIW, I have no idea what kind of steel my 1" tubing is on my low rider, some kind of steel, but it isn’t stainless. I didn’t know that when I bought it, but it has treated my just fine.
Exactly my point. When I got to the price of SS rails (originally they were supposed to be free from my neighbor) I started having second thoughts on the “small machine”. So yes, that’s the plan, save the SS for the LR2, and go conduit on a small MPCNC, making both very value orientated machines…
But I also echo some of what Jeff said, it’s not that I can’t afford to spend more $$$, but for a hobby machine, I just wouldn’t. But the low barrier to entry that V1 presented was impossible to resist. In other words, to totally abandon a different course of action (Workbee or Home Brew). Now once I get things built, will I be willing to spend $ in incremental upgrades? Depends on the value I see in them, and to be honest, how much I use either machine. For me, this whole CNC router experience has been a 10 year quest. I have a garage littered with 80/20, ball screws, linear bearings and shafts, control boards, power supplies oh my!, all proving how difficult these things are to build from scratch, with a bare bones garage shop, but I digress. The goal now is just to get the damn thing built! So if it’s DOM or SS or good old conduit, I’m sure there is logic in supporting all of them, and I just hope you consider continuing to serve both the high and the low end of the market…
Exactly why I built it in the first place instead of buying one.
For a normal sized MPCNC the is barely a difference.
plus or minus 1" on the 48". ouch…
Mine were exact cuts. Well, plus or minus a saw kerf.
Just wanted to add that the journey and this community provide the least expensive and most effective introduction to CNC and 3d printing skills. It’s a veritable college course for less than $1k (including the purchase of a 3d printer).
We should make some kind of diploma!
There are many, you’ll find them pictured in the ‘Things You’ve Made’ section. 
Your diploma is in the shape of a crown.
So far, there’s only been one. To graduate, you have to plasma cut it from steel.
There can be only one…
That’s not fair… 
Art imitates life …
Diplomas are a relatively low bar, and are more or less equivalent.
A masters thesis is a much higher bar, and they are all different.