My sugstion, have fun with them.....
Have you ever thought about just playing w/ different pieces and parts, a little sheet styrene and some extra time? I've started and almost finished one of my funest projects yet, a sci-fi space fighter based on absolutely nothing, it contains all spare/scratchbuilt parts..... since there's nothing it's based from.... I can mix all scales and all kinds of parts...... aircraft controls mixed w/ a mixture of auto/ jet engine fighter plane parts...... just sit down and goof around, enjoy yourself.... this hobby's supposed to be fun!!!! So step out of your bubble, and put some of the more common parts to a new and original use!!!