You should be able to resize the model to the real world dimensions. First go into Model Info>Units and set them to Millimeters. Then in the model space, get the Tape Measure tool. Measure the distance between two points making sure you click on both ends. Type the actual dimension and press Enter. SketchUp will ask you if you want to resize the model. Choose the affirmative answer. If you used components in the model, right click on each one and choose Scale Definition to correct the size. As for why it worked to 3D print your model, the exported .stl file has no units. 35 is just 35. When the .stl is imported into the slicer software the slicer is set up to millimeters and it all plays nicely. As an example, here's a thing I modeled in SketchUp using meters as the units. [image: Bido_Screenshot-1_9_20221_44_30PM.png] And the first rough 3D print. They snap right on to the 18mm dia. tube. [image: 51107454646_b7205eb035_4k.jpg]

Could you upload the SKP file for your part? You say you are using SketchUp 2015. If I remember correctly, that was a long time ago, after all, STL export was only available through a plugin. I don't remember enough of that plugin but there is probably a place to set export options. Is there a reason you aren't using SketchUp 2017? It has a native STL exporter and there are options to set related to size and such.

CleanUp should be in the Plugins or Extensions menu The name of the menu was changed from Plugins to Extensions later. TT_Lib is a bunch of common support files for a number of the author's extensions. You normally don't need to access them directly. Why are you using SketchUp 2015? Why not SketchUp 2017 Make?