I have seen many questions on Facebook and other forums for those that want to use Blender for 3D printing on how to change the units in Blender to millimeters. Hopefully this short tutorial will help out. The Blender version used for this is 4.1.1 but should work for any older versions. Below are the following steps to take. 1. When you open Blender, you see the default scene as shown below. Click on the icon shown by the arrow to select “Scene Properties”. 2. You will see all types of properties that can be changed but the one we want is labeled “Units”. If it is not already expanded just click on the small arrow to expand. Change the units from meters to millimeters. Just above that is a window labeled “Unit Scale”. Enter 0.001 and press enter on your keyboard. You will notice when you do this the grid in the 3D view will change. We will fix this next. 3. Click on the icon highlighted in the image below. It is labeled as “Viewport Overlays”. Where it shows “Scale” enter 0.001 and press enter on your keyboard. The grid should change to the appropriate scale. 4. To make this the default scale in Blender we must save it as the new start up file. In the image below click on “File” shown by the arrow and go all the way down until you get to “Defaults”. Move your pointer to “Save Startup File” and select. Confirm the change by selecting “Save Startup File”. You can now close out Blender and when you start it up again you should see the units set to millimeters. Once you are more comfortable in Blender you can save the startup file in any configuration you want by changing settings and saving the startup file again. For example, you can delete the default cube, camera, and light so you won’t see them show up anymore at startup. If you don’t want to change the defaults you can save customized Blender files (.blend) with any configuration you want. As an example, below I not only changed the unit scaling but added a wireframe outline of what my build volume for the Creality Halot Mage printer is. I also expanded the 3D tool add-on tab that is built into Blender so it would be ready to use. To do this all you need to do is customize your settings and then go to “File” “Save As” and give it a name like Halot Mage Setup. It will be saved as a .blend file and when you open it all the customizations will be there. Below is the same .blend file opened with an imported model. When you done with the model just make sure only it is selected before you export as an .stl file. I hope this will get you started using Blender for your 3D modeling etc. There are many video tutorials on YouTube, CGCookie.com, and Blender.org that can help you learn more.