Vocabulary Glossary - 3D Design & Printing

Overview

A reference for all key terms used in this curriculum. Terms are organized alphabetically.

Terms

Additive manufacturing - A family of processes that build objects by adding material layer by layer. 3D printing is a form of additive manufacturing.

ABS (Acrylonitrile Butadiene Styrene) - A common plastic filament, stronger and more heat-resistant than PLA, but harder to print and emits more fumes.

Bed adhesion - How well the first layer sticks to the print bed. Poor adhesion causes warping. Improved by using a heated bed, glue stick, or painter’s tape.

Boolean operation - An operation that combines or subtracts 3D shapes. The three types in OpenSCAD are union(), difference(), and intersection().

Brim - A flat ring printed around the base of a model to help it stick to the build plate. Removed after printing.

Build plate / print bed - The flat surface on which the 3D object is built. May be heated.

CAD (Computer-Aided Design) - Using software to create 2D or 3D models. OpenSCAD is a form of CAD.

Caliper - A precision measuring tool used to measure the length, width, height, diameter, or depth of objects to the nearest 0.1 mm or finer.

Clearance - An intentional gap added to a design so that two parts fit together with the desired level of looseness or tightness.

Constructive solid geometry (CSG) - A modeling approach where complex shapes are built from simple primitives using Boolean operations (adding, subtracting, intersecting).

Cooling fan - A fan on the printer that cools the extruded plastic as it is deposited, helping layers set quickly and maintain shape.

difference() - OpenSCAD command that subtracts one shape from another, creating holes or recesses.

Direct drive extruder - An extruder mounted directly above the hot end. Better for flexible filaments (TPU) because the filament path is short.

Extruder - The mechanism that grips and feeds filament into the hot end.

FDM (Fused Deposition Modeling) - The most common type of 3D printing. Melts plastic filament and deposits it layer by layer.

Filament - The plastic material used as “ink” in FDM printing. Comes on spools in 1.75 mm diameter rolls.

Functional requirement - A testable statement describing what a design must do. Example: “The marker must support the weight of a desk rolling over it.”

G-code - The machine instruction language that tells the 3D printer exactly where to move and at what temperature. Generated by the slicer.

Hot end / nozzle - The heated component that melts and extrudes the filament. Typically heated to 200-250C depending on material.

Infill - The internal structure of a printed object. Usually expressed as a percentage (e.g., 15% infill = 15% solid inside). Common patterns include grid, gyroid, and honeycomb.

intersection() - OpenSCAD command that keeps only the region where two shapes overlap.

Layer height - The thickness of each printed layer. Typical values: 0.1 mm (fine detail) to 0.3 mm (fast/draft). Affects surface quality and print time.

Linear extrusion - In OpenSCAD, linear_extrude() turns a 2D shape into a 3D object by extending it upward.

Module - In OpenSCAD, a reusable block of code that can be called with different parameters to create variations.

Overhang - A portion of a model that extends beyond the layer below it. Overhangs above ~45 require support structures.

Parameter / parametric design - A design approach where dimensions are stored as variables, so changing one number updates the whole model.

PETG (Polyethylene Terephthalate Glycol-modified) - A durable, moderately flexible filament. More impact-resistant and heat-resistant than PLA; easier to print than ABS.

PLA (Polylactic Acid) - The most common beginner filament. Bio-derived, easy to print, low-emission. Brittle under impact and heat-sensitive.

Primitive - A basic 3D shape in OpenSCAD: cube, sphere, cylinder. Complex objects are built by combining primitives.

Render - In OpenSCAD, pressing F6 generates a full, final 3D model from your code. Slower than Preview (F5) but required for export.

Retraction - A slicer setting that briefly pulls the filament backward when the nozzle moves without printing, to prevent strings of plastic between features.

rotate() - OpenSCAD command that rotates a shape around the X, Y, or Z axis.

Slicer - Software (e.g., PrusaSlicer) that converts a 3D model (.stl) into G-code instructions for a specific printer.

Stakeholder - A person who has a meaningful interest in whether a design succeeds - typically the person you are designing for.

STL file (.stl) - The standard file format for 3D models used in most slicers. Describes the geometry of a shape as a mesh of triangles.

Support structures - Temporary scaffolding material generated by the slicer to support overhangs during printing. Removed after the print is complete.

Tolerance - The acceptable amount of dimensional variation in a printed part. FDM printers typically have a tolerance of +/-0.15-0.30 mm.

TPU (Thermoplastic Polyurethane) - A flexible filament used for rubber-like parts: phone cases, wearables, shock absorbers. Harder to print than PLA.

translate() - OpenSCAD command that moves a shape along the X, Y, and/or Z axis.

union() - OpenSCAD command that combines two or more shapes into a single solid.

Warp / warping - A print defect where the corners or edges of a print lift off the build plate due to uneven cooling.

$fn - OpenSCAD special variable that sets the number of faces on rounded shapes (spheres, cylinders). Higher = smoother. Typical values: 20-100.