Full Size R2-D2 Build

The frame is aluminum. I got an older design years ago. I saw in your video that you have one of the newer ones.
Mine is setup to have the center leg able to retract/extend, and the side legs to adjust between 2 leg and 3 leg mode.
I have the same dome as you do, and several of the other outer shell parts are the same or similar.

Sadly, I have not done anything on it in a long time, been sidetracked with other things. I need to get back to it.