@ Gordy. I will try to explain why "Fantasy".
I have talk with a friend, Hans Trauner, who is expert for that time. He told me that nothing is correct at that figure for 1 century BC.
First of all there exist no proof for that kind of beard. Possible are Goatees.
No archaeological proof for a wild boar cape. He called it Fantasy. The collar (torque) could be possible but normally was found in women tombs, only a few time in men tomb. The Brooches (Fibeln) no archaeological proof for that period. Only some hundreds years before in women tombs (Hallstadt period) and not in that kind.
The dagger. Some parts are ok, but not the material, the decoration and the kind to carry him.
That part he is wearing at his right arm (Armberge) no archaeological proof for that period, only roundabout 1000 years before and then only wearing from women.
The tattoo. Only Cesar wrote one time about some British Celts with tattoos. And no tattoo needle was found until today.
He said he is not able to said what period that bust should be. Hope that helps a little bit
But I think it is a very good bust and I like it very much, but not a Celt
Ulrich