We report the design of a metal powder bed fusion system for in-situ monitoring of the build process during additive manufacture. Its open-architecture design was originally determined to enable access for x-rays to the melt pool, but it also provides access to the build area for a range of other in-situ measurement techniques. The system is sufficiently automated to enable single tracks and high-density, multiple layer components to be built. It is easily transportable to enable measurements at different measurement facilities and its modular design enables straightforward modification for the specific measurements being made. We demonstrate that the system produces components with >99% density. Hence the build conditions are representative to observe process fundamentals and to develop process control strategies.