Strobon Cree's (white is the brightest) placed on the rear arms facing backwards, they give an indication of the drone orientation.
If you want a lighter setup you can just use double sided tape or Velcro instead of the 3d printed mounts.
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The led's that attach on top of the drone don't help with it's orientation and when it's up in the air it could be shielded by the AC body from the ground view.
Mounting the led's underneath could affect the VPS (visual positioning system), so arm mounting is recommended