These are some of the sites that I use to learn how to build things. Some of them are props based, some are drone based, and some are just funny tech sites.
Giaco Whatever
https://www.youtube.com/results?search_query=giaco+whatever
Tested
https://www.youtube.com/user/testedcom
Rotor Riot (drones)
http://www.rotorriot.com/
Volpin Props
http://www.volpinprops.com/
Joshua Bardwell (drone / electronics)
https://www.youtube.com/user/loraan
NYC CNC
https://www.youtube.com/channel/UCe0IyK4ntgdPTTjsxjvyHPg
RC Model Reviews (anything RC)
https://www.youtube.com/user/RCModelReviews
James Bruton / XRobots
https://www.youtube.com/user/jamesbruton
Simone Giertz (Queen of crappy robots) – FUNNY
https://www.youtube.com/channel/UC3KEoMzNz8eYnwBC34RaKCQ
Punished Props
http://punishedprops.com/
Ed’s Junk
http://www.edsjunk.net/wordpress/
Luna’s Pupplets
https://www.lunaspuppets.com/
The Replica Props Forum
https://therpf.com