Tube glue. Well at least when the tube is about half full, it makes a good wedge for positioning parts...
Use either a plastic welder like Tenex which sets fast, or my favorite, good old laquer thinner. These melt the plastic together for a good joint, and don't get brittle with age. Frequently, it is best to hold the parts together and touch the joint with an old brush diped in your choice of "glue". The glue will seep into the joint by capillary action and form a good joint, also you do not get gaps in seams like if you use tube glue at the prescribed alignment pins that most kits have.
To glue clear plastic parts like canopies or headlights, Elmer's glue works wonderfully. It may not stick to the plastic as well, but it does not distort the plastic and dries clear.
As a side note, Modeling clay is useful for holding parts in akward positions while they dry.
Rust is great stuff for armour or that "used" look on vehicles. We have several methods for doing it.
Least complex: Soak steel wool in water in a glass jar. set it in your window and wait for it to evaporate off. If there is still alot of steel, repeat. Crush up what's left. Use a paint, whatever color trips ypur trigger, then dust it with your rust while the paint is wet. Nothing beats real rust for rust effects.
The more complex version requires steel filings and copper sulfate.... More on that later.
On an old truck, try painting it an overall rust color first, then paint your primer color, usually grey, then your actual color. By gently sanding, you can get effects like late 80's paint peel/sunburn (down to primer color) or the next stage, rust.
I've been experimenting with using Aluminum foil for dents. I've never been able to heat plastic, bend it, and have it look credible. If you take the foil, place it over the area to be dented, and carefully rub it down to match the curve. Carefully remove it, and set it aside. cut out the plastic that was covered. Place the foil back on the model and tack in place with glue or tape or whatever is handy. Use some form of instrument to make the dent. Pay attention to the direction of impact, like scraping down a pole. Afterwards, back fill the aluminum with the melted sprue (made by dissolving sprues in laquer thinner) and allow to dry. This gives support behind the aluminum. I supose you could remove the foil afterward, but I havent tried that yet. If this was a recent scrape, paint the foil with whatever color it is going to be, and re-scrape the dent. this will allow the metal to show through at the high points. (Note: don't do this to vehicles that have fiberglass fenders, it just doesn't go). Also watch the edges of the foil, they can be difficult to hide.
Where to put rust? Look at the world around you. With armour, most people make the mistake of making rusty tracks. If the vehicle has been standing for 12+ hours especially after a rain, the tracks will get covered with a bright orange rust. As soon as the vehicle moves, the grit in sand and soil will quickly polish the pads to a shiny silver (with the exception of the rubber pads that some tracks have). The inside of the track gets the most polishing where the sprockets and road wheels hit, but in sandy regions the entire inside of the track gets polished like the inside of a huge rock tumbler. On the otherhand, in sandy areas, sand tends to continuously fall down on the lower inside of the track covering it quite fully. Steel of exhaust systems quickly rust to a dark brown due to the high heats involved. Cars tend to rust where dirt, water, and roadsalt collect, ie usually lower parts of the wheel wells and around moldings. Note: some vehicles use painted on pinstripes instead of mouldings, pay attention.
Wear on military vehicles: Pay attention to where and how the crew climbs on board. Sandy boots are good at knocking paint off of high spots like bolt heads, hand holds, and steps. Watch for where metal rubs metal like coils of cable vibrate and rub paint off below them, tool that are clipped to the outside of the vehicle and edges and corners of storage bins. Skirts, bellies and sides tend to get scratched up from the terrain that they drive through. The Germans tended to keep their vehicles well cleaned, but if they are in action, off paved road vehicles get very dirty very quickly. Think about where the grime gets thrown.
Dull coat occasionally frosts or orange peels for no apparent reason. There is nothing quite as frustrating. Try mixing white glue and rubbing alcohol at about a 1:3 ratio and spray that through an airbrush instead. It dries dead flat and will not frost nor orange peel.
(Allan Burbank)
Here are some tips that I have found at a car modelers car book store that I think might help you out in the rough spots.
MAKING BELTS AND COVERS: This can be done two ways and used for many things. To make belts, blower covers, spare tire covers, even boots and tops, use tissue paper or a paper tower without the quilting. If you are making seat belts, paint the tissue paper with acrylic paint and let it dry. Once dry, it will be pretty durable and can be bent to make natural looking fold. When making a cover for something, get either tissue paper or unquilted paper towel. Cut the paper to a resonable size then soak it in deluted elmers glue solution (thin down with water). Then place the paper and mold it over the part and let dry till hard. Once it's dry, remove, clean the part molded and paint the paper form. Once the paints dry you have a cover that will fit perfectly over the part. (submitted by Zach Hastings)
WIRE SOURCE FOR LINES: When detailing my model I wanted to put in brake lines, I looked around and eventually found something that worked pretty well. Searching through drawers I found some ties for trash bags (the wire ones with paper on the outside) I found that by stripping off the paper left me with some pretty good wires for detailing, brake lines, fuel lines, ect..(submitted by Jake Hastings) (p)
DECAL TIGHT PLACES: Ever had a very small decal that wont stick in a very tight place?, try this, instead of using hot water and so forth to soften the decals, try placing it onto your tongue for a few seconds (about 40 seconds). I have found that the saliva softens it nicely, expecially after you have had a cup of hot coffee, all you do is then is wipe it clean and place it into the model. I have done this many times without the use of micro-sol and/or micro-set and it works everytime. (submitted by Ziggy Eichstadt) (p)
FINGERNAIL DECALS: I like to use fingernail design decals for custom and lowrider models.These are found at most beauty supply stores such as Sally's.They are different and are sure to gain more attention to your models. (Submitted by Antonio Holmes)
STRIPPING CROME AND PAINT: To strip chrome/paint try using Castrol Super Clean. It is cheap and usually available at local automotive stores as well as Wal-Mart and K Mart. On smaller chrome plated parts (kit bumpers, valve covers etc.) it will usually remove the chrome in a matter of minutes. I have found that it also works excellent as a paint remover. Depending on the type of paint used it will normally strip all the paint from a kit body overnight with no damage to the styrene at all. Happy Modeling (Submitted by Chris White)
SCRIBING LINES: I use a small machinists steel ruler and the back side of a #11 blade (turned slightly toward the ruler to keep it from "wandering") (Submitted by Paul Canney) Another approach is to use the adhesive labels from a plastic label maker. The kind where you turn a wheel to make each letter. They are plastic and quite strong. The glue will stick with out damaging the plastic or resin.And the bonus is that it won't slide on you the way a ruler will. (Submitted by Ken Kitchen) What Paul and Ken have both said are good Ideas. I have used both ideas at different times, the best thing I have found is a small steel scribing template from Verlinden Productions...(part no# 0280)It is used by the aircraft guys to scribe panel lines, it has squares, circles,log, short lines all kinds of shapes. It bends around curves and flattens back out....I got it at the local Hobbytown..($10.75) used it for a couple of years and it still looks new.. (Submitted by Gear Head) I use 3M FineLine tape as a guide for scribing new panel lines. The stuff is thick enough to work as a guide but flexible enough to allow for a gentle curve should you need one. For severe curves (such as radiusing the corner of a door panel) I use a plastic draftsman's circle template,taped in place on the body so that it doesn't move around. (Submitted by Pat Covert)