Hi Bob,
I'm inclined to agree that a plastic candle holder may be a fire risk!

DMLS sure is amazing. Ultimately though, it's a composite, so I wouldn't be sure of it's structural integrity for moulding purposes - particularly under pressure. Also, it's still very expensive, so it would be a costly way to find out that it definitely can't be used. Machined metal moulds on the other hand, are a tried and tested technique.

Good idea though.