[CAD] Illumination needs to have a fixed position

[beniroquai]

@ranranking I think we would need to have the illumination in a "well-defined" state so that it won't bend away. Like a snap-lock or something. Also, I discovered that the mechanism of bending it away enables us to have some sort of darkfield illumination if we wanted. So 3 states:

• bend away
• brightfield
• darkfield would be very cool. Would you mind adding this somehow?

[ranranking]

that was the thought of mine, i was tried to add some small hump to kind of lock the position. Was not sure if it can somehow work. Then i will rethink and redo it