Sometimes the work engulfs you. You can't get rid of thinking about various work issues. And it exhausts you. It would help to detach completely from it, realize how unimportant it often is, and think about something else. I've created a reminder to help me recall it more easily.
Load the three .stl files (or .obj files) into the Slic3er as a multipart object. Assign extruders to the parts and slice it.
Slic3er (1.37.1) had some problems: It left out a bit of material near the leftmost letter 's' and near 'w'. Printer had to print in the air in those places, but it recovered from it and the problem is not visible in the final print, almost. Maybe they'll fix the Slic3r in the future.