  We report on a method for using stereolithographic (SLA) additive
manufacturing to rapidly and cheaply prototype components for use in
high-vacuum environments. We demonstrate the primary vacuum contaminant from
freshly printed SLA plastics is water with no evidence of polymers out-gassing
from the material and thus the vacuum performance can be controlled with simple
treatments which do not involve surface sealing. An unbaked vacuum system
containing SLA printed parts achieved 1.9e-8 mbar base pressure whilst
retaining structural integrity and manufacturing accuracy. Preliminary results
indicate that our method can be extended to achieve ultrahigh-vacuum
compatibility by baking at higher temperatures. We further report on the effect
of atmospheric exposure to components and present evidence to suggest that
re-wetting occurs exclusively in the component skin layer, by showing that the
bulk mass changes of the material is irreversible on the timescale investigated
(< 2 weeks).
