Considered the large variety of models and their scales of reproduction, it is unthinkable to find what you need in hobby shops. So every prototype is hand made in the old traditional way. So, hacksaw, drill, files, sandpaper, creativity and a lot of “elbow grease”.
For this type of activity, which takes away a lot, but a lot of time, I use my favorite materials: plastic, wood soft and good glue.
Most of the work should done it by itself, but sometimes happens to use pieces of old kits or objects that are used to anything in reality.
This allows me to make a suggestion: sometimes you find strange objects that seemingly useless. Do not throw them away if you can keep them .. sooner or later you will find their modeling purpose.