You must completely finish the drawing in SketchUp ensuring that is a complete solid object and has no reversed faces. Solid means that if you filled it up with water nothing would leak out. Any small section that's not touching another edge or face would create a leak and would therefore not be printable. You then have to export it to an STL file converter. In earlier SU it was a free add-on. In the current version it's included. The SLT creates a 3D model describing all the exterior surfaces that can be interpreted by the slicing software. The slicer then creates the individual layer geometry that the machine uses print the object.
The resin printing system can produce layers down to 10 microns. I find that free-standing objects much small than 1 scale inch in O'scale are very fragile. If they're supported they will be okay, but if they're just hanging out there, they will break off. 100 microns is the best most string (filament additive printers) are capable of which is why I waited until resin printers were available at low price points to do the railroad stuff I'm now doing.
