Why not do the bricks with dark purple, on top of the light purple- practice on something first, you can highlight corners, sides or bottom of brick to give demention.
Well you are right, I do the majority of the poly coats THEN I paint the detail, then one last coat of poly.
I did my painting in a basement. You could do it in the bedroom- BUT don't plan on having her sleep there, and you will need to keep the doors closed and window open. I also liked painting outside if the weather cooperated.
okay- draw your image (or copy from your chosen artwork)
draw on paper. then use tracing paper (you know the really this stuff) this will help with the transfer because the paper is so thin.
Then place your transfer paper- it has black on one side, i think it's graphite. Put the black side down, place your tracing paper copy on top-tape in place for stability, then trace over the line drawing. Be sure you have it positioned becaue it wont come off easily.
Now I have to ask- you DID prime this first, right??? That will make a HUGE difference in the paint not absorbing into the wood. Then 2 coats of your color on top. If you could have I would have done a lt purple primer where you want the purple, but that's in the past.
So now you have your coats on- its time to poly (I suggest at least 2 coats for a lasting finish) THEN paint your details, then do your final coat of poly- no need to sand this last coat.
This is what I use for details
How about painting a purple Unicorn? You wouldn't have to do the whole body, you could just do head, chest and front legs and place in on a corner (like he's just coming around the corner of the castle)
Think about size and what you are trying to accomplish- is the unicorn half the height of the castle, smaller? whats your scale?
Does that help?