The color of the sliders is achieved by gluing colored paper to it.  That's how I did it, feel free to make any changes to the design. I included the template I used for cutting the paper :-)

Edit:

This is an old model of mine and I don't really remember how I got the two halves together but I guess that I glued it with a hot glue gun. I didn't expect this model to be so popular. I might recreate this model and add a version that is easier to assemble for all the motivated people in a few months so stay tuned :-) ( this edit was posted 14/7/2024 22:22)

Edit 2:

It is 21/9/24 and it kept bugging me, so I made a better second version (V2), I tested this version at 50% scale and it assebles much better (I haven't tested it in full scale, since my crappy V1 still works just fine). I left the design itself mostly unchanged just better optimised for 3D printing. It takes less material to print, rounded all the corners to combat warping, wall thicknesses optimased for 0,4mm nozzle and changed the sliders a little. If you decide to print it in full scale, please let me know how it went :D