Really glad to hear you enjoyed it so much! Level design involved much more trial and error than it did planning. The first thing I did was outline the structure of the levels, so I decided how many bulbs and how big each box would be. The principle here was to ramp up the size of the box before increasing the number of bulbs, to create kind of a zigzag progression. From there I mostly just placed the bulbs and batteries randomly and played a lot. Having friends or family to try your puzzles is a big plus.