The author remixed this model.
With the first version it was not easy to align the 2 base parts for glueing them together, therefor I added 3 bowtie like connectors.
The connectors will help increasing the glue contact area and helps with the alignment, the bottom bowtie might need a little re-work after printing, as of the thinness this should be easily be done with a utility knife.
Added also the top plate as printable version, following the principles of https://www.printables.com/model/273948-test-model-for-transparent-petg-printing and adding 1-2 layers of white PETG, would recommend having the white PETG on the build plate for best surface finish on the visual side.