Show HN: OpenSCAD configurable calendar 3D model (opens in new tab)

I think it’s the super low barrier to entry. When I first started 3D printing, I wanted to make basic shapes with decent dimensional accuracy. OpenSCAD lets you install a single app and start doing that immediately. It was easier for me to quickly learn the OpenSCAD syntax than it was to spin up on FreeCAD or Onshape.

There’s not many free as in open source alternatives out there. There’s traditional CAD such as Fusion 360 which gives you a limited amount of designs and is “free” for non-commercial use.

So then under the open source, own your designs umbrella you have stuff like FreeCAD which is similar to traditional CAD which means you have a learning curve.

OpenSCAD is programmatic which suits someone with a software engineering background. Plus being free in the sense of owning your designs.

Well, I personally just can't do 3D modelling any other way, if I had to use graphical tools to create it, it would be pain. On the other hand, writing code is a second nature for me, so even if it's a little inconvenient, it's still much better than anything else (for me).

I only used it once for modeling some procedural decorations in the shape of flowers. I did it on a long train ride and managed to both learn the language and do the models, so there's something to be said about the simplicity. If I had to do anything more complex or less artistic I would use other tools. Something python-based would be ideal.

> there are more expressive 3D modeling DSLs

Can you name them? I'm not being sarcastic, I just want more options :-) (if they are free and open source, just like OpenSCAD)

You can always insert a pause and swap to a different filament at a certain z-height.

As others have said, you can use M600 or a pause (depending on your printer) and swap filaments. The design specifically supports both use-cases, it can easily switch from all colors on a single height level to all colors having their own height levels.

You can use M600 to stop and load a new filament to use multi colour.

I need to take another run at CADQuery and Build123. I’m frustrated with OpenSCAD’s unstable kernel, but it’s still the easiest way to get a basic parametric design going from code.

I’m also keeping an eye on zoo (fka KittyCAD). It too has performance problems, but if/when it stabilizes it’s exactly what I want.

Easter calculator. The algorithm is roughly:

Sunday after the first full moon on or after Mar 21. If the full moon is a Sunday, then the following Sunday. The date of the full moon is not an astronomical one and its date is left as an exercise for the reader.

There are two Easters too - the Orthodox one involves the Julian calendar, the Roman (etc) involves the Gregorian calendar.

You could chicken out with a lookup table!

Wow, nice!

Actually, not much except the curly braces + semicolons, which makes it look like C, C++, Java and many others.

OpenSCAD is functional/declarative, so you can't change the state of a variable, functions don't have colateral effects, lists are immutable, and so on.

We also don't have for, while or if-else in the way we have in other languages. A for loop in OpenSCAD is only a way to repeat objects (= 3D objects, not POO objects), if-else are like a ternary operator for objects, the objects aren't values, and so on.

OpenSCAD has also some built-in less common features. One highlight for me are native vector and matrix multiplication, and other is the list index based on the name of the axis (list.x means list[0], list.y means list[1] and list.z means list[2]). But it lacks string and list operations, which would demand some FP-fu to write your own functions to manipulate them, just like the author did.

If you speak Portuguese, I gave a course last year about OpenSCAD. The slides are available here: https://lucasoshiro.github.io/posts-en/2024-03-24-openscad/

It supports both with a single toggle, either you use MMU/AMS in which case it's all on the same level, or you don't use it and all colors have a different height level making it easy to just M600/pause your print and change the color.

Designs of this kind don't leave that much poop, there's not much waste when it's only a few layers.

> Also how do you get on with the slicer with fonts.

Haven't had many problems with them, I usually enlarge the text until I'm happy. I also usually do $fn = 360 for OpenSCAD which uses so many triangles that you can't really see it not being round with your naked eye.