You are right, there are quite a lot about Celts but not much on the mail they wore. Not to fear, heres a picture I have of mail from a votive deposit at Tiefenau (where, reportedly, around 100 two-handed swords were found)...
https://i16.photobucket.com/albums/b...evotivedep.jpg
...the Ciumesti chainmail was apparently folded, rolled, and adorned with rosettes of bronze. I do not have a clear picture of this chainmail up close on my HD, so here it is in its, uh, crumpled glory...
https://i16.photobucket.com/albums/b...tedwithabr.jpg
...other depictions of Celtic mail can be found of the Pergamon Arch...
https://i16.photobucket.com/albums/b...2the1/mail.jpg
...the Vacheres statue. This could show a Gallic noble or a Gallic auxila...
https://i16.photobucket.com/albums/b...aGaulnoble.jpg
...this is a Gaul in what could be chainmail from Civita Alba...
https://i16.photobucket.com/albums/b...1/GEDC2724.jpg
...and the Kirkburn mail shirt, a reconstruction.
https://i16.photobucket.com/albums/b...nmail3-2nd.jpg
I hope this helps you see the possible styles, varieties, etc... that existed here and there in Celtica :yes:
I have a suit of mail myself, but I have not completed my Gallic warrior kit just yet. I promise I will post pics when I am done, though it will not be as good as Vasiliyi's chainmail progression pics. Great job, Vasiliyi, and I am envious that you have time to make your own suit from the beginning!