Thanks both I will let you know how I go.
Its white and green I struggle with, on the holmes wright I tried to look at the "rays" of light coming out from the dot...... if you imagine how you would draw a cartoon sun, a circle with lines coming out from it.... I was trying to use those. My theory being for the white light those lines would be longer, on the green light they would be shorter.... it didn't seem to work though!!
Anyone else tried something like that successfully, either on HW or Beyene lantern?
cheers
ES