Introduction
For redirection light from the sources (see modules and components) 90 or 180 degrees requires a prism or a light cable. But a prism would be much better, with lower losses of light. For the spectrometers that I use, the spectral properties of PMMA (Polymetylmetakrylat) plastic are sufficient. (I think PMMA is called plexiglas in Swedeish, or rather that Plexiglas is the leading brand of PMMA in Sweden). Stepping up optics from PMMA would probably mean PM7 glass and require a completely different ballpark of efforts.
Moulding kits
I think that I will probably have to mould the prisms to get the exakt measures I want. Here are som alternative kits to look into: