My god, it's really not that hard to figure out.
It's clearly
>>7568740In the green circle you can see the border between the bracket and the quarter tile and in blue you can see the ridge all plates have plus the little cut out for the stud.
The top part is obviously this
>>7569340It can't use a 2x3 with rounded edge, as said before the hole wouldn't be in the right place and more importantly there is no way to connect the lamp like in the picture using that piece
