I worried a little bit about the attachment of the 27-inch backglass monitor and the DMD in the backbox from the pinball. I've had indeed a solution, but I wasn't very happy with it and it would have been quite a botch - I'm just not a timber worm, but rather an electronic technician. Fortunately, I've got support from Thomas Beckmann, who is working on a DIY Visual Pinball cabinet with his buddy for themselves and with whom I am in contact regularly for sharing experiences since some time. He had a wooden frame left over from his project, which I could use directly with a small adjustment. At this point, many thanks to Thomas for his support, the frame takes me forward a big step.
I also ordered a proper Plexiglas bezel from a Plexiglas shop - with this shop I've had good experiences on my retro arcade project.