Print on top of finished print?

[fred_dot_u]

I've attached an STL file of the orginal nut, reduced to twenty percent and chopped at the point just below the lettering. There will be a solid bottom if you have your slicer settings correct and the lettering should appear in a normal manner.

I used Meshmixer, imported the big nut. In the import screen, I set scale to 0.20, ensured that uniform scaling was turned on and snapping is turned off.

Zooming into the much-smaller model, I then selected Edit, Plane Cut. The settings for that is to fill the cut mesh, not many things there. Use the blue arrow to move the slicing plane up and down until it reaches the desired location. I determined that by looking at the bottom of the letters, the "base of the valley." When it disappeared, I had the plane too high, and moved a "tiny bit" downward from there. Accepting the results, exporting the model and here you have it.

Even if you learn that oh-so-powerful Fusion 360, Meshmixer can be faster and easier for the small stuff.

I like both of them as well as a number of other programs. Don't restrict yourself to just a couple, learn as many as possible. Even Tinkercad has value. I just realized that I could have done this in Tinkercad too!