OpenSCAD

OpenSCAD occupies an unusual position: you do not drag geometry, you write code that describes it. Script on the left, live-rendered shape on the right. It sounds backwards, and for one class of work it is the best answer available.

The archetypal use is functional parts. Say you need a mounting bracket: hole spacing 32 mm, plate 3 mm thick, M4 screws. In OpenSCAD those are variables — write it once, and the next device with 40 mm spacing needs one number changed and a re-export. Need a whole set of sizes at once? Write a loop. That kind of parametric generation is far more laborious in a GUI modeler.

A side benefit is that the model file is text — it goes into Git, produces readable diffs, supports collaboration, and can be generated by other programs. Open hardware projects love this, and a large share of the customizable models on Thingiverse are OpenSCAD scripts underneath.

Its limits are equally clear: it is wrong for organic shapes and styling. Sculpted surfaces, flowing fillets and artistic forms are painful here — that is Blender's territory. What it does well is disciplined mechanical and structural parts.

One situation to be explicit about: the tagged stable release is still openscad-2021.01, with no new stable version for several years. The project itself remains under active development and the official site offers continuously updated development snapshots — in practice, the snapshot is what the community runs, and new capabilities such as the faster rendering backend live there. This is simply how the project has always released, not abandonment — but you will see two options on the download page, and knowing which to take matters.