3D Printing How-To's

I use Fusion 360 for design, Bambu Studio to slice and print, on a Bambu Lab P1S with AMS. These steps are for this setup. You may be able to do similar steps with a different setup, but you will have to discover the specific details.
These tips are not for beginners, and assume you have a working knowledge of the software used. 

Embedded or Inlaid Colour (Color)

This is about embedding different coloured shapes or text into a surface, so it is flush with that surface, not embossed nor debossed.. This method uses the design tool and the slicer. To add text using only the slicer, see further below.
Forget everyone telling you to "colorize" ("colourise"), it's too much effort, takes much longer, and is much less accurate than this method I discovered. Let's get started ;-) ..

Fusion 360/Design Steps

• Create a new Sketch on the surface/plane where you want to embed the coloured shapes or text.

• Add any shape(s) or text.

• Finish Sketch

• Extrude and set the Operation to New Body. Set the dimension to -x mm, so it "extrudes" back into the surface. You will get a new body/object for each letter of text or each shape you select to extrude.

• Export your project as STEP, STL should also work. When I tried exporting as 3MF, it messed up the positions of the text object in the slicer.

Bambu Studio/Slicer Steps

• Import your project into the slicer (Bambu Studio or Orca)

• Click Split to Objects (this will not be available if there aren't multiple objects per the steps above)

• On the left sidebar select [Objects] instead of [Global]. Click the little List icon ("view all objects settings"). You will see the list of objects and their assigned filaments. If there are lots of objects, it may be because there's an object for each letter of text.

• Assign the desired filament/colour to each object. Much easier if you have an AMS. You must already have multiple filaments available to do this. Add filaments as needed.

• Right-click on the plate, away from any objects -> Select All objects, then right-click on an object -> click Merge to bring them back into one object ready for printing.

• Slice, Preview and Print as usual

When you slice, if you get a "Serious Warning" that you have conflict between objects, then you missed the previous step to Merge the objects.

Another way to add text.. using only the slicer

You can also add text to be flush with a surface from inside Bambu Studio (or another slicer like Orca)..

To create flush text, add the text to the location desired and get it setup as needed (text height, depth, font, etc). Once text is setup, go to the objects field on the left hand side of the screen select the text, right click and select change type, then change the type to "modifier". To change the text to a different color, right click on the text and select change filament. Change to the desired color of filament. That simple. Now the slicer will just create a print with the model and text flush with each other. 

More Efficient height-based Colour Changes Per Layer

Sometimes you are printing a multi-color object and it's designed for colour changes based on height only. When you use the Colourise (colorize) tool in your slicer, and select by height, this works but is often not accurate. You will notice when you slice, that you can get excessive filament changes. If you preview and use the right-side slider to move up/down the layers, you can see that colour/filament changes are happening within layers when you don't want them to! You want them to happen only between different, specific layers.

So we need to make this more accurate, and only change filaments between layers.
To do this in your slicer (Bambu Studio or Orca), do a first slice, then go to the Preview tab, use the right-side slider to move up/down to the layer where you want to change filament and right-click -> Change Filament, and choose the filament to change to. Then Slice the plate again, go back to Preview and check you can see the colour change as you slide up/down the layers. Check how many filament changes the slice summary shows.

Happy 3D printing!