Where should a beginner start?

If you just want a first print, start with Tinkercad. Once you make cases or parts that fit together, move to one parametric CAD program. If you want free with no online account, FreeCAD is the main choice.

Can I sell things I design in a free version?

FreeCAD, OpenSCAD and Blender are open source and fine for commercial work. Fusion's free tier is for non-commercial home use, and Onshape Free does not allow commercial use. Read the maker's current terms, because they change.

Do I need to know programming for OpenSCAD?

You write short scripts, but only with shape, move, rotate, union and cut commands. Non-programmers can start. The payoff is that changing one variable gives you a new part instantly.

CAD for 3D printing: Tinkercad, Fusion, Onshape, FreeCAD, OpenSCAD, Blender

CAD for 3D printing comes in two families: parametric CAD, where every dimension is a number linked to the others, suited to parts that must fit; and mesh modellers, where the surface is a free collection of triangles, suited to characters and art. Choose by the part, not by which program is most famous. This lesson compares six programs makers actually use, plus the free-plan terms worth knowing.

The usage terms here were checked in October 2026. Commercial software changes its terms, so check the maker’s site before you commit.

Parametric vs mesh

Parametric (solid): draw a 2D sketch, give it dimensions, extrude it, then add holes, fillets and so on. The program remembers every step (the history). Go back and change an early number, and every later step is rebuilt.
Mesh: the surface is many small triangles. You sculpt, pull and drag points freely, but nothing knows that “this hole is 3 mm”. Changing a size means editing each part by hand.

The STL you send to the slicer is also a mesh. Design in parametric CAD and you keep an editable original and export later (files are the next lesson).

If the brief says “must fit with…”, use parametric. If it says “should look like…”, use mesh.

Pick by the brief: fit means parametric, looks mean mesh

The six compared

Program	Type	Runs in	Cost / terms	Best for
Tinkercad	combine basic shapes	browser	free	first parts, kids, name tags
Fusion	parametric	installed + cloud	free personal-use tier, non-commercial, limited editable documents	cases, mechanisms, assemblies
Onshape	parametric	browser	Free plan non-commercial, all documents public	working across machines, sharing
FreeCAD	parametric	installed	open source, free	parametric everything, no account
OpenSCAD	script (CSG)	installed	open source, GPL v2	parts resized by variables
Blender	mesh / sculpt	installed	open source, free	characters, figures, free-form

Tinkercad: a first part in the first hour

It opens in the browser. Drag boxes, cylinders and letters, stack them, mark some as “holes” to cut, group, and export STL or OBJ for the slicer. Ideal for kids and anyone who wants something on the bed today.

The limit: there is no parametric history. With dozens of overlapping shapes, making the case 2 mm wider means moving every piece yourself.

Fusion and Onshape: commercial parametric CAD with free tiers

Fusion (Autodesk) has a free personal-use tier for home-based, non-commercial design and making. Autodesk limits it to 10 editable (“active”) documents; others are kept but must be swapped back in before you can edit them, and the licence needs renewing periodically. These terms have changed several times, so check the Fusion for personal use page before a long project.

Onshape runs entirely in the browser, from any computer. The Free plan states it is for personal, non-commercial use and that every document is public, so others can find it. Do not keep client work or ideas you are not ready to show on that plan.

FreeCAD and OpenSCAD: open source, no account

FreeCAD reached version 1.0 in November 2024. It greatly reduced its biggest old problem, “topological naming” (edit an early sketch and later features break), and added a built-in Assembly workbench. Version 1.1 followed in March 2026. Use PartDesign for most printed parts. The interface is busier than Fusion’s, but it is completely free and your files stay on your computer.

OpenSCAD has no mouse modelling. You write a script saying where the boxes are and where to cut, and it builds the shape (CSG: adding and subtracting basic solids). It exports STL, OFF, AMF and 3MF (since 2019.05). It is best for parts you want others to resize, such as a case that takes a board size and gives you a new case.

Blender: when looks matter more than size

Blender is a mesh 3D program for sculpting characters, figures, masks and decorations. The 3D Print Toolbox extension (Blender 4.2 LTS and newer) checks for non-manifold (not closed) geometry, calculates volume, and exports STL, OBJ and PLY.

Watch out: set the scene units to millimetres before you start, or the part arrives in the slicer at the wrong scale. It is not the tool for parts that must fit to 0.1 mm.

Worked example: a board case you can resize

The brief: a case for an ESP32 board of 52 × 28 mm, 0.3 mm clearance on each side, 2.0 mm walls.

Inside = 52 + 2 × 0.3 = 52.6 mm and 28 + 2 × 0.3 = 28.6 mm
Outside = 52.6 + 2 × 2.0 = 56.6 mm and 28.6 + 2 × 2.0 = 32.6 mm
Switch to a 55 × 30 mm board → inside 55.6 × 30.6, outside 59.6 × 34.6 mm

In parametric CAD (or OpenSCAD) you change only the board numbers and the rest follows. In Tinkercad or Blender you move all four walls and the floor yourself.

// OpenSCAD: change the top line, get a new case
board = [52, 28];  clear = 0.3;  wall = 2.0;  h = 20;
inner = board + [2*clear, 2*clear];
outer = inner + [2*wall, 2*wall];
difference() {
  cube([outer[0], outer[1], h]);
  translate([wall, wall, wall]) cube([inner[0], inner[1], h]);
}

A 0.3 mm clearance is a starting point; every printer differs (see printing parts that fit and printing a case for your board).

Common mistakes

Using Blender for a case that must fit. It looks great, but nudging sizes by 0.2 mm is painful.
Typing raw numbers everywhere instead of variables. In Fusion or FreeCAD, use parameters or a spreadsheet with names like wall and clear, then change them in one place.
Keeping only the STL, not the source file. Three months later you want to move a mounting hole and have to redraw the whole part.
Client work on a public free plan. The design ends up where anyone can find it.
Switching programs every week. Pick one parametric tool and get fluent. Sketching and constraint skills carry over between programs.

Next lesson: STL, 3MF, STEP and OBJ: what is the difference

Sources

Circuits and code were tested on sample boards. Boards differ in pin layout, so check your board's pinout before you power anything.