Ok, But Really, What's Printing Like?

Hopefully if you’ve gotten this far, you have a decent sense of what 3D printers can do and how they do it. But you may be asking "what is it really like to print with one." How can I possibly measure and communicate what the experience is like? Abstract metrics! For comparison! Based on my own arbitrary opinions! (Hey it's either this, or a bunch of bland numbers.) Bear in mind that these are based on my personal experience with printers I have owned. Other printers that are built similarly may perform very differently in some of these categories. If you're serious about getting a printer, make sure you do your research beforehand.

FDM Printers (for me, a Creality Ender 3, Creality CR-10S, Robo 3D R1+)

• Visual - FDM printers are a blast to watch. If you are the kind of person who likes watching documentaries with factories or robotic assembly lines, you need an FDM printer. It is like a magic pen that draws up from the ground into the air using robot parts. I mean, come on. 
• Noise- This can vary a lot, both objectively and subjectively. 3D printers CAN be very loud. They have numerous fans moving air constantly, and the stepper motors can "hum" pretty loudly (although somewhat musically in my opinion) as they are moving the extruder around. But with some extra upgrade effort (or extra money for a well tuned machine) you can have a printer that is actually pretty quiet. There is also a subjective aspect to it, because even while my printers can be noisy, I don't find the noise annoying or offensive, but some people really really do.  
• Speed - Slow. Slooooooooooooow. SO SLOW. This is just part of the nature of 3D printing. Everything takes longer to print than you think it possibly could. It's fine. It's a good way to develop patience. Just bear in mind that the time it takes to print almost anything worth printing is going to be measured in hours. There are lots of factors involved in determining how long a print takes, so you do have some control over it (assuming your slicer lets gives you that control.). 
• Smell - The printer itself has no smell, but there have been some materials I have used that let off a mild chemical smell when i first open their bag or when it melts in the extruder. PLA has basically no odor so unless you plan on printing with some of the harder materials, smell won't be a problem. 
• Tidiness - This may vary from person to person, but I think FDM printers are reasonably clean and don't generate messiness around them. Many people use glue sticks or hair spray or painter's tape on the printing bed to help the print stick, and that goop can get messy. For the past couple of years I ONLY print on textured or glass beds (with heat). So my prints are living proof that it's possible to not have any goop or tape to deal with. The biggest mess otherwise is the scrap plastic from the print supports, and other little plastic fragments that wander off the nozzle or the print bed somehow. 
• Heat - An FDM printer can add a lot of heat to a room. If you use a heated bed, you're looking at a decent size surface cranked up to 50 C(122 F. Printers like the metric system, but we Americans can love them anyway), and it's putting off heat the entire duration of the print. The extruder is much hotter. It's smaller and more contained, but it still contributes to heating the air around the printer. 
• Frustration - Well, yeah, sometimes. Just like anything else. There are times when things just don't seem to work right no matter what you do. But generally they are consistent machines, so if you take the time to figure out what is making it fail, you can usually address the issue (and feel like you won a gold medal when the dumb print finally finishes properly. In general, they're a lot like computers in this way.
• Footprint - It varies from printer to printer, but because the total build area is a decent size, and surrounded by a steel frame, they can have fairly a fairly large footprint. Basically, if you know the print bed size, take that and roughly double it to get some idea of how much space it will take up.
• Upgrade Potential - FDM printers are fantastic for tinkering. They are composed of fairly simple and common components so it's easy to buy and install upgrade parts. Better still, it's easy to PRINT some upgrade parts, and help your printer help itself. (3D printing parts for my 3D printer is one of my favorite things. It's so meta.)
• Safety - generally, I believe FDM printers are safe. They do have very hot zones, so you must be careful not to touch those when while the printer is heated up or running. Basically give the printer the same level of care you would give an oven or a power tool in your workshop. Because FDM printers have heated electric elements, there is the remote potential to be a fire hazard. As such, it is recommended to never leave the printer running unattended. Having said that, there are safety mechanisms in place to shut the printer down if it detects that it is overheating. 
• Fun - Obviously. 

Resin Printers (Elegoo Mars)

• Visual - Resin printers are not as fun to watch as FDM printers. Since all the printing magic happens inside a vat, behind a light-filtering cover, you can't even see the actual print in progress for an hour or so. Once the print rises enough to be visible, it's neat to see, but the watching the process is really just watching it go up and down a little bit every few seconds.
• Noise - Mine has fan noise, but only one stepper motor that doesn't run continuously, so it makes about as much noise as a desktop fan. 
• Speed - Still too slow. Resin printers print their layers way faster than FDM printers, BUT they print way more layers than FDM printers do, so it still takes hours to finish most prints. (Although my printer is one of the slower ones now, so other people may have different experiences with speed.)
• Smell - Pretty much all resin I have tried release some fumes, but some are less intense than others. Some printers have air filters to prevent fumes from circulating out into the room air (but I can't say whether they are effective.) If you have a sensitivity to odors or fumes, just be aware that it's just part of resin printing. Even "Plant-based" or "natural" resins are going to have some chemical nastiness to deal with.
• Tidiness - Resin printers are super messy by nature. The whole system depends on syrup. And it's the kind of syrup that doesn't wipe off easy and just feels like it keeps spreading. You have to avoid contact with skin, so you're almost always wearing gloves, which then get resin on them, but you don't know that because you're wearing gloves. After that point, everything else you touch with those gloves might have to be cleaned too. After the print is done, you typically need to rinse it in isopropyl alcohol, so most people keep a container with some in the general area, which can also cause some mess. For these reasons, if you care about the surface your printer is on, you better protect it with some kind of liner or cover, or the resin and alcohol could easily mess it up. 
• Heat - Nope. I've never sensed that it added any meaningful amount of heat to the air around it. I can sense just a little heat when the UV lamp turns on. 
• Frustration - Yeah, but in different ways from FDM. In my experience, resin printing is more consistent, because there are so few moving parts. The same file will typically print the same way each time with less chance of random failure than FDM. The flip side is that if there is a problem, there is almost nothing you can tweak or adjust on the printer itself to correct the print, so you have to go back to the computer and slice it all over again with new settings. In my case since my printer is in my garage (which I don't really recommend by the way, but it is what it is), and my computer is across the house, it's a pain to keep going back and forth. Also, as with all 3D printing, the bottom layers are the most important, but you can't actually see if they stuck properly until the printer has been running for 45 minutes or more. That's a lot of wasted time if you're trying to get your print to stick to the bed and it keeps failing.
• Footprint - My resin printer is very compact. It could fit on a desk, but because of the mess and smell, that would be a bad place for it.
• Upgrade Potential - Not much. I have personally 3D printed 2 upgrades but they are "quality of life" upgrades and don't impact the printing quality. I have also added a removable magnetic print bed. Other than that, there is very little that can be changed out on a resin printer. 
• Safety - In my personal and non-legally responsible opinion, the printers themselves are very safe. The resin is not. Direct skin contact can cause rashes, and fumes can affect the lungs with prolonged exposure. If you have small kids in the house, then you need to make sure the printer is secured and inaccessible to them, and that all resin bottles or vats are stored out of reach.
• Fun - Obviously. 

Sections

• The Basic Basics
• Software: Slicers, Control Software and 3D Design Tools
• Common Species of 3D Printers Found in the Home
• Ok, But Really, What's Printing Like?