This A5-sized template can help you draw perspective lines in isometric views. The accuracy of the perspective effect can determine the success or failure of the
If you want an A4-sized version, you can scale the model up by 2 times in the slicing software, or print two copies and stick the long sides together.

Follow the steps in the picture to draw all the lines. During the drawing process, I found that it was faster to use the side of the template to draw the upper and lower lines, so I also added an STL file of a template without small holes to reduce the printing time.