I tried to decode that, but I gave up halfway through. Something about renting office desks or whatever. Don't tell me there's anyone in Germany who would actually use the word in speech
It's a perfectly fine German word, even if I just made it up myself. It's a renting place for desks for the office of assistants to employees of repair workshops for lightweight drills.
And of course, is it ein kleine schöne Dünnbrettbohrerreparaturfachwerkstattsangestelltengehilfenbüroschreibtischverleih, or do you see den kleinen schönen Dünnbrettbohrerreparaturfachwerkstattsangestelltengehilfenbüroschreibtischverleih, or does it all actually have something to do with kleinem schönem Dünnbrettbohrerreparaturfachwerkstattsangestelltengehilfenbüroschreibtischverleih and can you spot the mistake?
Yes, it should be "ein kleiner schöner", apart from that all is perfectly fine nominative, accusative and dative.