  Atomic vapour cells are an indispensable tool for quantum technologies (QT),
but potential improvements are limited by the capacities of conventional
manufacturing methods. Using an additive manufacturing (AM) technique - vat
polymerisation by digital light processing - we demonstrate, for the first
time, a 3D-printed glass vapour cell. The exploitation of AM capacities allows
intricate internal architectures, overprinting of 2D optoelectronical materials
to create integrated sensors and surface functionalisation, while also showing
the ability to tailor the optical properties of the AM glass by in-situ growth
of gold nanoparticles. The produced cells achieve ultra-high vacuum of $2
\times 10^{-9}$ mbar and enable Doppler-free spectroscopy; we demonstrate laser
frequency stabilisation as a QT application. These results highlight the
transformative role that AM can play for QT in enabling compact, optimised and
integrated multi-material components and devices.
