Whiteboard
I put a magiboard in the observatory so that Tamsin & I could discuss & draw what we were seeing through the scope. As it turns out, this is a very useful way of obtaining flats for processing any astrophotography.
The board is evenly illuminated by a fluorescent light on either side. As long as it is cleaned thoroughly it has provided good flats for scopes & lenses alike. It only fails for the fisheye lens :-)