Custom ships or vehicles
can range from micro-sized to those in the 3 3/4" scale. I don't think
many customizers have done ships or speeders in the 12" line yet....what
a huge project that would be! Even the Hasbro / Kenner line of vehicles
are scaled down in the 3 3/4" line (ie. the Falcon would be about five
feet across if it were true to scale to the 3 3/4" figures). Think about
how large a Sandcrawler or AT-AT would be!
Most customs of ships that I've come across has been the "weathering" or dirtying-up of existing toys. Blaster marks or even severe damage such as torp hits have been accomplished by literally melting or burning holes the ship's fuselage. But these techniques are for adults only ... NEVER attempt to do this without adult supervision, good ventilation and fire safety materials at hand! Most weathering can be very achieved by "dry brushing" or air brushing.
Dry brushing is a technique where you take your dry paintbrush and put a very little amount of paint on it. Wipe off most of the paint, and then apply it sparingly around panel edges, or edges of the ship that would take the brunt of oncoming debris when flying (ie. nose cone, front of wings, etc.) Darker brushing around engine exhausts will give the ship more realism as well. Always layer from darkest to lighter colors...sometimes even a brushing of silver looks great too.
Air brushing is a very effective technique, but requires a large cash input for the tools and materials plus a fair degree of skill to be used properly. This method would be something you could move up to if you were going to dedicate a great deal of time and money in the hobby.
Model kits - Sometimes hobbists will mix parts of ships together to make new models. They may even purposely keep the parts looking different, to represent a cash-deficit Rebel force that had to cobble repairs from whatever they had. Speaking of models, model car, plane or ship sets can provide wonderful additions to vehicles. ILM does this, so why can't you? (Did you know that those silver rings in Luke's training remote on the Falcon were actually wheel wells from a model car kit?)
"Found" parts - Always keep your eyes open for interesting shapes and "gadgets" to add realism and variety to your customs. Computer parts, plastic rings from drink bottles and nearly anything may be just the perfect addition to your ship, vehicle or droid. I've used "found" items such as the inside workings of computer mice, thumbtacks, metal tubing, springs and screws in some of my customs.
For example, I made this
custom Treadwell droid a few years back before Hasbro packaged him with
Aunt Beru. He was made from metal tubing, toothpicks, two thumbtacks (the
"eyes"), a screw wrapped with a rubber ring (at the base). Wire and sculpey
make up the rest of this droid. I used the plastic ring from a fruit drink
bottle to imprint the treads in the base, and a gear from an old watch
to imprint the wheels in the sculpey.