Is there a why to draw a straight rule line outside of object My object has different parts but overall when it is combine together it need to be specifically 64 cm, so I need to draw a specifically straight rule line to use it as a reference. Is there a way to draw a straight rule line or any better idea?
You can use grid for precise measurements


Switch to orthographic view (View > Orthographic)
Use top/side view (View > Viewpoint)
enable Absolute Snap to Increment


When zooming, the grid will go from meters > centimeters> milimeters.