Tried my hand at two colour overlay today, the giraffe pattern wasn't intentional but it gave me a chance to play around with screen filler. I also found that the colours mix better whilst listening to death metal, total fact.
After some half split searching and foul cursing finally managed to resolve a few issues with the exposing process, nothing is ever too obvious.
Pro tip: Don't buy shitty positives, it'll only make you sad, I don't work for these guys but a shout out to Positivity Ltd Super duper fast, friendly and positives black enough to eat light.