“All this slicer stuff”:

So an STL file stores the shape of an object by defining triangles by their vertices in 3D space. Kind of like a giant 3D connect the dots puzzle. I’ll note here: This is a close but imperfect approximation of a shape, especially curved surfaces are actually highly faceted. Other file types like AMF or 3MF or something might be able to do true curves, I’m not sure. An STL only stores the surfaces of an object, it is up to the program that is reading it to interpret the interior as hollow or solid or whatever.

Your 3D printer can’t understand an STL file. It’s a fairly simple machine, it’s got a couple heaters, a couple fans and a few motors, and it needs to be told what to do with them in very direct terms. Most 3D printers use a command langauge called G-Code for this; a line of G-Code might look like this: G1 X35.386 Y181.683 E27.01397 I actually copied that line out of a G-Code file. It’s commanding the printer to move the nozzle from its current position in a straight line to an X, Y and E position. E is the extruder axis, get used to that 3D printers actually track motion in 4 axes. G-Code is designed to be human readable and writable, and I suggest you learn a little bit about how it works for reasons I’ll get to later, but for the most part you’re going to use software to automatically generate G-Code, using a slicer.

A slicer is what we call 3D printer CAM software. 3D printers usually create objects by laying down thin, flat layers of plastic that can be described in 2D terms, so the software “slices” the model into a bunch of horizontal cross sections to arrive at a 2D shape, and then uses an algorithm to draw that shape using lines of extruded plastic. G-code has commands for curves and such but most slicers just use a series of very short straight lines.

The general algorithm is going to be something like “draw a few laps of this layer’s outline. Color inside the lines, and then move the Z axis up a fraction of a millimeter and do it again.” Things like how many laps it does drawing the outline, how densely to color inside the lines and in what pattern, along with what temperatures to heat the bed and nozzle among many other things are adjustable in the slicer’s settings. Almost all of the 3D printer’s behavior is actually decided by the slicer.

Including the little routines it goes through at the very beginning and end of the print. You’ll find a page in the settings that allow you to write custom G-Code that it will copy paste at the beginning of each file, at the end of each file, and sometimes between each layer. I have a Prusa-style bed flinger printer, and I added a command to the end script to run the bed all the way forward as if presenting the model, to make it easier to get to for removal. This is why I said it’s wise to learn a little about G-Code, so you can add customizations here.

Additional tools: I like to keep a pair of needle nose pliers near the printer to grab oozed filament, some side cutting pliers for snipping filament, I have some dedicated allen wrenches for the common adjustments on my machine, and a razor scraper for removing prints from the bed. Your machine may have different features than mine so adjust accordingly.

Unless you live somewhere with a really low humidity, get something to store your filament rolls in. I like the Sterilite 54 Quart Gasket Boxes. They will hold a dozen rolls of filament. Put humidity meter and a big cloth bag of silica gel in there to keep it dry. Bake the silica gel when the humidity starts rising to regenerate it.

The 4 liter cereal storage containers work well for storing single rolls. You can print a spool holder that will fit in them so you don’t have to take the filament out of the box to print with it.

Get or make a filament dryer too. The filament usually comes wet even though it’s packed in a vacuum sealed bag.

You best spend some time on YouTube looking at introductory videos.

I’m a big fan of Gunplamark’s remixed filament box.

https://www.printables.com/model/1305684-the-ultimate-cereal-container-filament-drybox-offi

Look at the remix files. There’s a better roller design by CMYK

https://www.printables.com/model/1339511-precision-single-bearing-spool-rollers

You’re going to need a scraper. Print your own or buy the plastic replaceable razor scraper (the blade itself is plastic so it can’t hurt your build plate)

You will also need a deburring tool.

An STL file describes an object/shape. This needs to be translated into actual print instructions such as move to X/Y position, squirt plastic, move again, etc. This is what a slicer does: It “translates” from a shape to actual print instructions. I’m not sure, but I’ve always assumed that it’s called slicing because it takes the 3D object and creates many vertical slices with print instructions.

I don’t know about your printer specifically, but I guess it takes Gcode (which is what you get as output from a slicer) like most other printers? I suggest you grab PrusaSlicer as it’s very flexible and supports a lot of different printer defaults. Load your STL in there, slice it, transfer the result to your printer, and you should in theory be good to go.

Tip: Start with something small.

What’s your goal, to take random designs other people made and print them, or to make your own stuff for fun or for some practical purpose?

The first original thing I’d made was a box to hold double-A batteries.

The slicer converts models into code to suit your printer. I use CURA for that.

Just ensure that you have your bed and extruder temps set right, and you pick an infill setting you like (I go 15-20% and Cubic). Make sure to preview the model and ensure that any significant overhang is supported. The bed on your machine autolevels but for anyone else, level your bed before starting your first print.

Only other software you need is 3d modeling software to make your own models. I’ve used Blender and FreeCAD but more expensive professional tools will work too.