Hidden Strength Achievement in The Talos Principle II

There are three green holograms to collect in this DLC. Two are easily collected like any other collectible: by just running into them out in the open world. One is right behind Puzzle 8's room, and one is amongst the trees next to Puzzle 21.

The third is located inside Puzzle 9, and you will unavoidably see if when you complete the puzzle. However, unlike all other collectibles, you need to solve your way into this one. Puzzle 9 ends with using three RGB converters in the final room to get into the area with the Progress Wheel. In the previous room, you should still have an Inverter directed at the Blue Receiver on the wall. What you first need to do is put to RGB converters in the final room near the doorway (one should be the Red and Blue Generators to make Green, and one should be that Green plus the Blue Generator to make Red). Make sure both are near the doorway leading back out of the final room. Now, take the third RGB converter out into the hallway, connect it to the green and red RGB converters so yours in blue, then connect it to the Blue Receiver on the wall. This allows you to take the Inverter from the previous room and bring it with you into the final room. Bring all three RGB converters back in there too.

From there, you can actually solve this the exact same way as Puzzle 8, where you have three RGB converters and an Inverter and need to bring two RGB converters past a barrier. The solution would be too difficult to describe in text, so refer to the video in Revelation (100G) if you need to see a video guide.