<p>I am new to 3D printing. I have a Longer LK5 Pro. I was making a part that has raised letters, and wanted to have white letters on the black part. I used a Post Processing script on the Cura program called &quot;change filament&quot;, which is supposed to stop printing, retract the head, and allow you to change the filament. Mine just keeps on printing. I've tried &quot;pause&quot; and done the filament change, but unsuccessfully so far because of blobs deposited on the letters.</p>
<p>Any suggestions?</p>

I've done it a few ways depending on the desired effect I'm after.
Manually pausing the machine is what seems to come out best. If you design for it, you can sometimes have it pause while it's over infill and therefore has no blobs to worry about. I haven't looked into doing it automatically, but perhaps it's possible to pause partway through a layer.
If the design doesn't have to be flat, then I'll do a solid colour and the last top layers another colour with the design cut out. This is to my mind optimal as you get a bit of texture with the design inset as well as different colour and makes for a nice clean method.
The other way was z-hopping which is an idea I got from a Youtube video. Cura has a setting for this. Basically you can make the nozzle lift when it moves. You split the colours into two separate objects and you print in one colour. Then you change filament and print another colour as a separate print right over the top of it and the nozzle hops over the original print.