>>11489810I already had the big Disney castle a couple years ago when I was given another one for my birthday and decided to MOC them together into a huge castle.
I'm an architect so most Lego I can do in my head but sometimes I'll do some sketches and order Bricklink parts if I need them. My Disneyland castle was 2 of the new recolored Florida castles plue 6 BrickLink orders to complete.
Because it was a replication of a real building I just looked at pictures. The biggest challenge with Lego as a medium besides cost is getting the proportions correct for mini figure scale, especially with their limited selection of windows.