I am thinking about getting a 3D printer.
What does one need to look for feature wise?
Many of them are chasing the features forwarded by Prusa (and people will argue about that but I've been watching knock-offs chase them for years.) Technically Prusa is RepRap so open source, but they have been innovating and releasing most of it to OpenSource so they are at the tip of the spear. This means that they are a little more expensive (it's a real company with real people) but you will often find the features and ideas more fully baked and supported with a Prusa.
So, you asked about features. Look at the Prusa site and then look for other companies supporting the same. Nearly every printer on the market will do 99% of anything you would ever want to do these days. Don't get dazzled by a print bed that's 20mm larger and think that's going to matter. I've been "restricted" to 250x250x200 for as long as I've had a printer and there have been
maybe one or two times I had to change my plans. Larger prints are exponentially slower, so scaling things down and/or printing them in pieces is often a better plan. Most all print models are tailored to the same class/size of print bed.
One thing on my latest printer that I would really miss if I didn't have it anymore is the textured magnetic flexible removable bed. The textured bed was a game-changer for me - I highly recommend it. It seems small but it made a big difference in print finish and my ability to get challenging prints off the bed.
I've seen them that support 2 or 3 filaments and color change, restart, filament out detection
I keep telling myself that color change is something I need, yet I've never had it. You can do a layer-based color change with most single-color printers now. If you look at
these coasters, you will see what I mean:
Restart has been incredibly helpful. Filament out detection is relatively new for printers and some works better than others.
@Thorrak has a model older than mine and his did not work correctly but mine does. If you let the filament run out you are almost guaranteed a partial teardown.
screw drive vs. belt drive,
open source firmware,
touch screen vs. dial
various print sizes
one had 2 extruders
A screw drive is technically more precise, but it's all about the package and the capabilities of the printer. Don't judge a printer solely by what you think the creator should have done - look at how they work. The belt drive on my printer is quiet, precise, and easy to work with. The printer firmware has progressed to the point where it outputs one of the best print qualities available. So long as the software (firmware) and the hardware are well-suited to each other, things will go well.
I love OpenSource, and these printers would not even exist were it not for them. That said, aside from philosophical differences, there's not a reason to worry about this unless:
- You intend to customize your firmware; or
- The printer you choose is so new/flawed that you will depend upon a robust community support model
I spoke about the print size above. In the Prusa line, there's a mini and a regular one. Having said "size doesn't matter" I'm going to turn right around to say I'd get the standard Prusa (or another brand around that size) for brewing-related projects.
Touch screen vs dial only matters while you set it up. After that, you can use something like Octoprint and you rarely will use the printer controls. This is not an area where I would spend time or money worrying about it.
Two extruders is a color print choice. It seems like a great idea ("no waiting for filament changes!") but in practice, it reduces your bed size along the Y-axis by 2X the distance between the nozzles. It's only ever going to be something you want if you have very specific and frequent color print needs. It's also more difficult to calibrate and keep that way.
another came with five spare extruder tips - how long does an extruder tip last?
I never have had to change a nozzle. So long as you are not constantly printing abrasive filament, you won't either for the practical life of the printer. I tried to change one once for a not very good reason and I won't do it again.
I like the ones that are 90-95% assembled, really not interested in full assembly, seems like too much of a pita
I'd encourage you to re-think this. 3D printing is not and will never be (at least in our lifetime) like buying a computer printer. Tinkering is required and encouraged. To that end, building yourself one (like the Prusa kit) is recommended and not too bad if you give yourself the time and a decent workspace to do it. You will learn things about your printer that may be helpful later on.
any other things that I am missing, feel free to toss in ideas or things I need to think about
It's obvious by now that I have and recommend a Prusa. It's more expensive than most of the others, and "they make you put it together." This is my second Prusa and I am not at all sorry I've spent the money. "Buy once, cry once."
Do look around though. Look for the community and how it is supported. How frequent are the commits in the firmware and other software repositories? This is an indication of how actively supported the printer is.
I know people with Enders, and I know they like them. Knowing what I know and seeing both I would buy another Prusa. Not trying to knock anyone here, and it is a slightly religious/political argument, but you asked for opinions.