3D Printing

Learn how a 3D printer works. Get inspired. Make your own stuff. It is a wonderful time to be innovative. Connect things together.
— Bre Pettis

3D printing is a manufacturing process that builds three-dimensional objects layer-by-layer from digital 3D model data, typically using materials like plastics (e.g., PLA, ABS), metals, or composites. Unlike subtractive methods (e.g., CNC milling), 3D printing adds material only where needed, reducing waste and enabling complex geometries like lattice structures or conformal cooling channels. It spans applications from rapid prototyping in engineering to custom prosthetics, food fabrication (e.g., chocolate), and even biological tissues.

For home hobbyists, there are two main kinds of 3D printing: FDM and SLA.

• Fused Deposition Modeling (FDM) extrudes thermoplastic filaments layer-by-layer through a heated nozzle, excelling in durability but struggling with fine details (<0.1mm). Plastics like PLA, PETG, and TPU are the most common filament materials.
• Stereolithography (SLA)/DLP Resin Printing, conversely, uses UV light to cure liquid resin into hardened layers, delivering sub-50µm resolution, smooth surfaces (ideal for miniatures or dental models), and faster print speeds for small parts.

My only experience is with FDM printing on an Ender 3 S1 Plus.

Use cases

Some use cases for at-home 3D printing:

• Practical prints like templates, soap dishers, tile spacers, and so on.
• Custom organization
  • Gridfinity
  • Storage walls
• Décor, especially mass media franchises with geek appeal.
• Toys: boomerangs, flexible dinosaurs, and the like.

Sometimes, makers combine prints with non-printable parts. For example, the Gridfinity system includes optional wells in their bins and bases for gluing magnets, allowing the bins to snap into place.

Models

Pre-made 3D models are plentiful. I prefer Printables as a catalog site, but I've used several others. Many designs are free, some makers charge for their designs.

You can also create your own! I mostly use Tinkercad for modeling, though I have also used others like OnShape and Blender. Some of my most successful designs are a 4-inch drain cover for our downspouts, a blazon for the Durfee family, a template for making Starfish retrospective layouts in my Bullet Journal, a medical tubing holder, and a replacement drive shaft for our juicer. I've experimented with Manyfold to catalog and manage my models, but I don't have that many and it feels like overkill at this stage.

Anatomy of a print

Unlike a 3D model, filament is subject to gravity, necessitating additional print structures like:

• Infill, thin walls inside the print to give it structural stability.
  • The higher the infill density, the stronger the print, but also the heavier the print and more material is consumed.
  • The choice of infill shape can provide different print properties. A few common options:
    • The gyroid is an infinitely connected periodic minimal surface containing no straight lines, making it a good at supporting stress from any direction. Honeycomb is also good for this, but consumes about 25% more time and material than gyroid.
    • Rectilinear is used for heavy infill, forming a rotated grid pattern inside the print.
    • Adaptive cubic creates spaces for air pockets, while using less material than cubic. Air pockets can allow a model to float, act as insulation, or can be filled with resin for decorative effects.
• Supports, which allow overhanging parts of the model to print at the desired height.
• Skirt, a thin ring around the base of a print. Most slicers begin with a skirt to establish a smooth filament flow as insurance before starting the first layer of the print.
• Raft: a horizontal latticework of filament added to the base of a print for stability. These are more common with poorly-adhering materials like ABS.
• Brim: a thin layer of material around the base of a print that helps hold down the edges of your print.

Printing Workflow

These general steps are true of both FDM and SLA printing.

1. Model Preparation
   • Import a validated 3D model (e.g., an STL, 3MF, or OBJ file from Tinkercad or another modeler) into a slicer.
   • Apply printer and filament configuration settings (e.g. print speed, nozzle size, nozzle and bed temperatures).
2. Configuration
   • Adjust parameters to suit the model:
     • Layer height (0.1mm–0.3mm for PLA)
     • Infill pattern (grid, gyroid, …) and density (5–20%)
3. Validation
   • Run a "dry print" simulation to check for:
     • Overhangs (> 45° may need supports)
     • Z-wobble (uneven first layers)
   • Export G-code to a printer via SD card, USB, or Wi-Fi.
4. Print
   • Load filament, change the nozzle (if needed).
   • Select the G-code program to run and start the sprint.
5. Post-print (optional)
   • Remove supports, clean up print artifacts though sanding or epoxy coating
   • Attach non-printable parts
   • Prime and paint, for example, lettering on tools or inking dice.
     • In cases like FDM miniatures, painting is an integral step unless you have a multi-filament 3D printer.