Scale Model building has been a hobby of mine since my childhood. Although I mainly build out-of-the-box, I also tried to some complete scratch build models or to use several kits to build something different.
It's not so surprising that I am most intersted in building ship models, especially German warships of World War II. Besides models of the a U-boat, the well known Bismarck or the Prinz Eugen, I wanted to make models of the never compeleted Kriegsmarine projekts, like the Seylitz carrier conversion, or the huge H-class battleship. Since you do not get such models to buy, I had to learn how to modifiy existing kits to create the models I wanted. It took some time until the result was ok. The first model - the Sedylitz - was not that good, but the later ones, especially the H-class battleship or the Odin hybrid warship look quite good now.
Besides ships, I also build some aircraft and vehicles - World War 2 and modern.
The quality of my models improved since I started to use an airbrush instead of a normal brush. It needed some time to lean how to use this tool correctly, but models like the Panther tank could not be made without one.