I'm not claiming to be an "expert" either.
If you can program in Python, VB isn't more difficult (just a little different).
You can write code that is triggered by event linked to the placement of of the part.
Placing each part would trigger a unique event (1 of
.
Set a variable to indicate "part X placed"
If the other 7 parts have been placed. Then change the screen color
If you change the color of each part as it is placed then that could be your "placed" variable.
Biggest problem will be determining which event you will trigger from.