This is a very affordable 3D printed optomechanics to attach two posts in 90 degrees to each other.
It comes with 2x M6x8 steel set screws for fixing the posts positions.
All DIY-Optics.com optomechanics are highly compatible with other industry standard optomechanics. (Thorlabs, Edmund Optics, Optosigma ..etc.)
See drawing for further dimensions.