FDM printing uses a filament of various types, heated through a hot end, to build up a model from a print bed. The filament comes in a spool, and you can have a literal rainbow of colors that you can print in. FDM printing is a lot slower than resin printing, but generally has larger print beds to print on, so you can get larger models to print.
The traditional FDM printer uses an XYZ gantry to do its printing. The X-axis is your print head traveling along an arm going left-right in your build area. The Y-axis is the print bed, and that will move forward and backwards. The Z-axis moves the arm of the X-axis up and down (traditionally only up during a print.) The print bed is heated to help for the filament to adhere. Most print beds use a special coating to help with filament adherence, my favorite is a material called PEI on a spring-steel plate that is like magic to help filament stick to the bed and you flex the plate when done and your prints just pop off. Other bed surfaces can be glass, tempered glass, borosilicate glass...these will usually give you a print bed without warping that can happen with metal beds. In addition to the bed heating, people will use adhesive substances to help the prints stick...things like custom-made adhesion materials, painters tape, regular school glue sticks, and hairspray.
An FDM print begins as a does a resin print, by taking an STL file and running it through a slicer. The most commonly used slicers are Cura and PrusaSlicer. You set up basic settings within your slicer telling it the printer type, the filament type, the nozzle size, nozzle temperature, print bed temperature, and layer height. Layer height pretty much determines your quality, in combination with the nozzle size. The smaller the nozzle size and lower the layer height, the more detail you will get, the fewer and less pronounced the layer lines will appear, but it will also increase your print time, a bunch. Part of what you need to determine is what level of detail you want vs how long you want it to take.
Behind the scenes there are hundreds of other settings that you can play with and tweak to get your printer to perform at peak speed and details, but once again, this is a real art to get these settings tweaked.
The most commonly used filament is PLA (polyactive acid) which is made from corn starch as it's primary component. There is no smell or off-gassing from the melting of PLA. It does a great job of creating simple models, but it is somewhat brittle. This is all I have ever printed with. The other filaments, like PETG and TPU...these are more difficult to print with, because you have to print at higher temps and PETG off gasses so you usually have to have it in an enclosure.
For the most part, models that have been made to print with FDM in mind don't need to have supports. You can add supports to FDM prints, but they are pretty terrible to remove and will slow you down, so you want to always try and print without supports.
Bed leveling is really at the heart of being able to get a good print from an FDM printer. Automated bed leveling is becoming more and more common with consumer level printers, but even that will need some fine manual adjustments. StAraight up manual adjustment requires using what they call "the paper test", where you move the print head to the 4 corners of the bed, bring the z-axis down to zero, put a piece of paper between the print nozzle and the print bed, and then adjust the height of the bed using knobs until the paper is just catching between the bed and nozzle. Once you get your leveling dialed in, you can go for months without having to re-level... but as soon as you move the printer, or replace the nozzle or the print bed, you will need to re-level.
Recommendations: I have had 3 FDM printers, an Ender 3 pro, an Ender Cr-6, and a Prusa Mk3S. I was pretty happy with my Ender 3 pro, and knew pretty well how to manage and troubleshoot any issues with it. I was seduced by the CR6, because of its promises of auto bed leveling, and it printed pretty well for me for about 6 months until it just went to hell and I couldn't get a print to work to save my soul. So I dropped the big money on a Prusa. I couldn't afford the pre-assembled version, so I built it myself. Took me about 12 hours to build. But it printed great. I got beautiful prints off of it, and the auto bed leveling was a thing of beauty. And it worked great for about a year. But right now, it's just a paperweight. I can't get any of my prints to stick to the bed. Everything I've tried just won't work. I've replaced multiple parts. Super, super frustrating. I'm about to punt and try and sell this one at a discount and buy one of the new Ender 3 V2 Neo printers. That's the printer that Tom Tullis over at Fat Dragon Games is recommending right now.
Speed...FDM printing is not fast. Depending on your layer height, larger prints can take over 24 hours to complete. Bunches of smaller prints on a single bed can take a long time as well, because unlike resin, you're not curing an entire layer all at once, you're having to travel all over the bed to lay down a layer of filament for each piece. I think the longest I've had a print run is like 39 hours or so.
Bottom line...3D printing has a learning curve. You won't be perfect out of the gate. You will get frustrated. You have to learn how to maintain and repair them. It is time consuming. But it's also magic, when you consider that you can go to a site like Heroforge, create a miniature that looks exactly like you imagine your character, and then 3 hours later you have the mini in your hand. I've slowed down a lot on my 3D printing, but its there when I need it. I have to get my FDM printer going again, because I am starting up a new project and I have a bunch of terrain I need to get ready.
Regardless, after seeing the fume hood into 5 gallon bucket trick, I was thinking I could set that up on a side table and maybe use my Tamiya cement without also losing touch with reality for a few hours every time....and then I figured maybe it would work for 3D printing ventilation as well, but yes space is always a consideration with these things...
