C'mon, you know you want a Voron....

I am making the jump to core XY personally. Decided to do a Hypercube with some of the Hypercube Evolution parts downsized for 2020 extrusions. Only glitch I'm running into is they're a pain in the ass to enclose for printing with ABS. Cartesians have them beat in that regards, but have a larger footprint so it's a catch 22.

Water cooled hot ends sound interesting....need to look into that.  Pretty sure you need a chimera type hotend for soluables.  I don't imagine they'll play nice with a diamond that I want to use. A cyclops I imagine will be much the same.

My first 3d printer was an ender 3 that I decided from the get-go to make dual extrusion.

The setup was not that hard but it did require replacing practically everything. I would have come out money ahead to just buy a higher dollar printer to begin with, but I did learn a lot, I guess.

Anyway, dual extrusion with a y adapter is not that hard to set up, although optimizing my retracts was sort of hard for me (ended up with trial and error... whatever you settle upon will be based on the length of tubing between your adapter and hot end nozzle). If you use a volcano or  volcano style hot end th3d and triangle labs sell a y adapter that will thread in, which is pretty cool.

But I found that using PVA was a pain in the ass just because of the nature of the filament. Even from a drybox it popped and hissed so I had to dehydrate it to use it. It was expensive per roll but that wasn't really a big deal because you could set it to only build the interfaces out of pva and build everything else out of your structural material.

Anyway, when I tried using it with anything other than PLA I had other problems. Lots of oozing when I tried it at petg temps, which wasn't surprising l guess. Just sort of made a mess. I know HIPS is the proper dissolvable filament for ABS but it needs limonene to soften and is expensive to boot so I never tried it. Perhaps I didnt give it a fair shake but if I knew then what I know now I would have gone the route of something like the Palette Mosaic. Seems to be much more well-regarded than the Prusa MMU but I have not used either. 3dprinting nerd had a video recently where he did pla prints with petg interfaces instead of pva using a mosaic 2, and that would be really easy and cost effective. Well, the petg would be, the mosaic not so much.

Now that said, doing multicolored PLA I never had an issue, although I found myself constantly wishing I could do more than two colors, so I just ended up painting anyway. I'll probably end up just taking the second extruder off honestly because the novelty wore off.

Additionally I saw videos of The 3d chameleon at the MRRF and it looks a bit convoluted but certainly effective. Might be worth checking out too.

Sorry if the post is a bit all over the place but there are lots of options now... the tech is changing so rapidly. The low cost of the 3Dchameleon makes me want to give it a shot in 4 color.

I'm doing the same thing. Prusa Bear frame stretched to 420mm on the Z axis. I'm also building a Zaribo Mk3 Rev 3 type frame right now with a 420mm Z.

@Rat_Patrol

What are you planning to do for axis end stops?

How do you do that with the Duet?

I've heard the sensorless isn't quite as precise, but I've never used it. Keep us posted on that one.

You know what, I missed the BLtouch you listed earlier. I thought you were going to use sensorless for the Z. Disregard. :-)

What is your Z height going to be? I should be getting my longer verticals tomorrow?

For a Bear frame you can get steppers that have built in lead screws that will get you 420mm from Zaribo. I picked up some 500mm extrusions for my Z. My machinist friend is going to cut them down to 459mm for me. That will match the steppers perfectly.

Just keep in mind that the Volcano is designed to print fast and move a lot of filament through there quickly.

Where I see people run into problems is trying to go for too much quality with one.
Smaller layers and slower speeds has the filament moving through the longer heated zone very slowly.
This increased dwell time can put too much heat into the filament and cause issues similar to heat creep.

Not saying it wont do it, just that it wasnt really designed for it, and def something to be aware of when setting up the slicer.

Interesting on the holes.

I usually size them to exactly what will be going through.
This ends up with them being a bit snug, then friction ream with whatever will be going through there for perfect fit.
Basically just chuck whatever is going to go through in the drill and let it heat and melt its way through. Drill bits spinning the wrong direction work well too.

Mad scientist is an incorrect term, that has become mainstream.

The correct term is angry engineer. 90% of what the movies term as science is actually engineering. Death ray? Engineer. Killer robot? Engineer.

Looking good!   I like the wide stance on the hot end carriage rails.

that's a big boat!