Super simple droid build, orange caps hold two part base together. The uploaded size creates a 6" ball, approximately 7.5" tall. Ball is hollow if anyone wishes to build electronics. Another one-off birthday present for my daughter who is in love with BB-8.
Print six Body_Caps and Body_Rings, print two Body sections. Body_Rings hold the two Body parts together, Body_Caps fit inside Body_Rings to hide seams. I was pleased with most of the fit but it did require some shaping and sanding. I recommend printing one Body_Ring and Body_Cap after you print the Body sections and adjust as necessary.
Credit for original design goes to Disney and Industrial Light and Magic (thank you for the inspiration!). 3D files were created in Cinema 4D based on visual interpretation of images posted on the web.
Update 2.0: All dome files have been modified, download them all for a complete upgrade. Added an orange detail ring to the bottom of the dome to better match the real BB-8. Parts fit snuggly, if you have a heat gun you can soften the plastic just enough to mold it to a matching piece. Go slow and don't overheat the piece or you may be printing it again!
I've added a 'Light' version of the body file. If you don't need the spherical interior this file will reduce the amount of plastic used for the print.
Update 3.0: New side panel files have been created, download all 'caps' and 'inserts' to upgrade your BB-8! I've been working on these for a while, I recently found a good resource on how the panel lines work out. I've left the original cap file online, it's been renamed to 'BB-8_Body_SimpleCap.stl'.
Update 3.1: I've added a set of 'F' panels, apparently my reference photos had a flipped image and there was a different panel that I had not mocked up. I've also improved the Main Dome file with higher polygon count (4x) so it doesn't have the 'facets' that the original one did. The middle detail ring (file 'BB-8_Dome Middle Ring.stl') was also improved to match the new dome file. Along with that is a slightly modified small lens (within the 'BB-8_Dome_Lenses.stl' file).
Update 3.2: I've added a single color dome that has panel insets and lines. There was a request for a one piece dome that could be printed when the user didn't have multiple filament colors. Look for file 'BB-8_Dome_Simple.stl'. There are overhanging structures so I recommend printing with supports.
There is also a new B insert (BB-8_Body_InsertB_arm.stl) with the popular 'thumbs up' attachment. You almost certainly will needs supports turned on. After the file is printed the arm can be inserted into the socket and glued into place. The torch will need to be glued to the end of the arm. Printing the original B insert and the new B insert should allow you to exchange the panel as desired.
Update 3.3: A request from one of the makers printing their own was to rotate the side panels 45° to better match the actual droid. I have applied this slight change to the 'light' version, as well. As a bonus I have created a 'whole body' version that can printed in one go so you don't need to assemble it later.
I've had many compliments on the fit and finish of the parts, be forewarned that the tolerances can be tight. Everyone's printers have different capabilities. Gently warming the pieces with a heat gun can make things fit easier.
Let me know if you are interested in any other modifications!