Brand new to train horns

So I have been fascinated by train horns for many years. I once had a Hornblasters setup on an old truck of mine.

The one horn that I’ve always wanted was a Nathan K5lla.

I know that I can find refurbished setups online, but just to satisfy my own curiosity, if I wanted to build one piece by piece (ordering the individual air chimes), how does one go about doing that?

And if it is possible, which chimes would I need?

Thank you!

a K5LLA would be made up of the 1L,1,2,3,4 bells and a low mount manifold.