Read this: Here I am adding my model of ANOTHER FLOOR for a garage with a parking lot standing by the road - this model is on my profile!!. It is easy to print. Just be careful when printing larger areas to avoid twisting. I recommend printing on 3Dlac and removing the print from the base only after it has cooled down.

This model can also be used as a garage on its own without the previous model from my profile! Just don't print the small roof on the last sheet.

For assembly, just use glue. The assembly is simple and you can see it clearly from the photos here. you just need to glue the individual parts together. I recommend not gluing the roofs so that it is easier to display cars inside the garage.
The cars in the photo and the workshop equipment are not included!!! These are not my models.

There is beige color in the slicer for printing transparent filament into the window. The other colors are as they should be.
Enjoy the exhibition of models in this diorama. Add a photo in the comment with your workshop equipment and your cars.