Out of Foam Board!
I often find that a P-51, Corsair, Spitfire, and P-40 are modeled pretty often. All of those planes are single engine fighter aircraft. Twin and quad engine bombers are more common in Balsa. The type of aircraft that I rarely see, Twin engine Night fighters/ground attack aircraft. These planes are rather interesting, and I can't find many. Dynam just released a P-61 Black Widow, but besides that I can't find any kits or PNP night fighters. I didn't even know that many of these full scale aircraft I could only name the Black Widow. I know that this will make some people confused, but I found many aircraft in a video game. I don't really play any video games, but I saw a historical Youtube Video on the IL-2 and noticed that the footage was from a video game. The game was called War Thunder, and since it was free I checked it out. My favorite aircraft that I didn't even know existed before were the DO-217, DO-17, JU-88, and BF-110. These aircraft are all interesting and I fell down a rabbit-hole researching them. In particular I like the JU-88, and think it would be a wonderful Foam Board model. Without this I wouldn't have known these planes existed. I also wouldn't have heard of a weird thing the Germans did where they pointed 20mm cannons and 7mm mgs straight upwards in an attempt to down bomber flights without being seen, and it worked. If you wanted some inspiration for a new design I would recommend checking it out, and you don't even have to play it because there is a family tree list of aircraft.