I found it a chore as most have in regards to leveling the build platform. I even tried to use a level app and my smart phone. That didn't help. One day, I was watching a show about the Pyramids and wondered if this ancient tool called the "A Frame" could help. I doubted it would at first, but gave it a try.
When printing you'll need to scale up to fill the size of your build platform.
I used those little ball shot fishing weights, hot glue and some fishing line to make the pendulum. Put a little gold fingernail polish in the center recess and colored the fishing line black with a sharpie so I could see it better.
I put it horizontal on the platform parallel to the front edge and get it level (using the 2 front screws) then I put it vertical parallel to the left edge and get it level, by adjusting the screw to your left, etc...around the 4 edges always adjusting the screw that was not turned yet only.
It should be almost perfect at that point. Maybe a minor tweak on one corner or another was needed and you're up and going in minutes instead of hours of leveling as I've read some people have endured. Hope this helps !