BabaJ

I am led to believe online that STL files can combine all 4 of those meshes. But I can't figure out how to make an STL file with multiple separate meshes in Houdini.

On one hand you're saying combining 4 meshes then in the next wondering how to make separate meshes.

I do 3D printing but send out to print shops and don't use a 'home' type unit.

I've used .stl for the most part but also .obj

What I know about .stl is that 'you' can't store information like color attributes on/in a .stl file.

Maybe you can, I've never needed to but have noticed when working on my model that has many group and attributes that as soon as I save out to .stl all those groups and attributes automatically get stripped from the model, i.e if I import that file to view there are no longer groups/attributes.

So I don't see how you can manage to assign colors to seperate parts of a .stl file.

But like you say, you can if you assign filament colors to different designated files. That sounds like you're doing the assigning/matching on the machine side; Not the machine reading inherent information like color in the file.

When I use a Merge SOP on my 4 meshes and then pipe that into a ROP Geometry Output node, the resulting STL file only appears to have 1 object

Yes, it is one object of 4 meshes. But no information which distinguishes the 4 meshes from each other, besides the inherent information of the physical separation;

Which for some cases allows one to send off files for printing in single files that have interlocking parts/assemblies.

.OBJ files though can save out color though, so you might want to try that.

Does your printer support .obj files? and with color?

It seems like you have to research your own printer on what file type and how color information should be stored in the file to do what you want.

litote
Thanks everyone. I somehow manage to find the wrong syntax listed for the function on a search, it had things in the wrong order so it didn't make sense. Thanks for confirming this.

You might find the SideFX Vex Functions page usefull in the future:

https://www.sidefx.com/docs/houdini/vex/functions/index.html [www.sidefx.com]

I'm using H21 daily build 21.0.562 and have no issues with changing Line Size, Point Size or Point Marker Size, respectively with:

Display Options: world > Geometry > Wire Width

Display Options: world > Geomtery > Display particles as

Display Options: world > Guides > Point marker size