I've used horse and human hair in resin with no problem as long as you keep an eye on it as it's curing.
You could cut a shape in the reverse of the setting so the hair showed through behind the cab?
This is one of the human hair ones - difficult to see but the hair had no bubbling, and was quite pretty! The bubbles were deliberate on the left. It was about a boy named Peter - his first word was bubbles, his nickname is Pi and the stone is Pietersite
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