title_body: How can I build a drone similar to a DJI Mavic 2? I want to build a drone with the same functionality as a DJI's Mavic 2. Are there any books/videos/guides available? What would be involved? 
  
  I need a flying machine that:
  
  
  has a good enough camera for short films
  has at least 25 mins of flight time
  is small and portable
  has an object sensing system, so I don't wreck it :)
  has a object tracking system to track people, cars, etc...
  
  
  Its main purpose is "object tracking" for short films.
  I know it will not be easy to build, but have the time and money to do it. I just need to know how.
upvoted_answer: Everything you requested is possible in a home-built unit (EXCEPT: object sensing and tracking.)
  
  I'd recommend the painless360 youtube channel.  Lee has detailed build videos on just about every kind of RC model that flies as well as tutorials about radio gear, GPS, ESC, batteries, camera gear, etc.  They are excellent and you can follow along with the builds.  It makes building your first model a great chance of success.  His channel is amazing especially if you are new.  All the lingo, terminology, etc are explained there in some way in literally hundreds of videos.  This may sound like a shameless plug for his youtube channel but I've literally spent hundreds of hours watching his stuff since 2015 and learned so much in the process.  If you are new to the hobby, this is a must.
  
  Painless 360 YouTube Channel
  
  As for the sensing and tracking features, it would be very hard or impossible to build one that would do all those things effectively for less trouble and money the aforementioned Mavic series could.  Things like object sensing and tracking are still very proprietary software options and you're not going to make this yourself currently.  As stated in the previous answer: Just buy it from DJI if you really need those features.  Otherwise, build your own.  It's a blast.