I remixed the 'Bolt sorter' of JavyJavy [https://www.thingiverse.com/thing:4695864]:
"Sorting tool for Bolts and Nuts Metric including Size of thread and bolt also length."
What I changed :
I reduced the height of the model (15mm instead of 20mm) in order to save time and material.
I recessed the letters instead of having them stand out.
This does not remove the nice effect of changing the filament color for the few upper layers.
I left just one of the four hanging holes as I believe that is enough.
Printer brand: Anycubic
Printer: All-metal Mega
I printed the model with a border but it really depends on the behavior of your printer.
The bottom later of big flat models can sometimes warp and a border prevents this.
I does not consume much time or material and it is very easy to remove for such a model.
10% infill is enough. Maybe 5% is probably OK.
The model took 13h to print...
With 0.2mm layers, there are 75 layers. I changed the color at layer 66, leaving 9 layers of white on top of the black.
Maybe less layers of white would have been OK, but not less than four if you want the white to cover the black.