You just bought that cool looking model car you have been wanting and just got it home. Now that you have opened the box and looked at it you are at a decision point. Just how much do you really want to put into the details? Most plastic model cars today come painted a basic neutral color so that model manufacturers can offer them to the public at more affordable prices. Unfortunately this means that you, the model maker, must put a bit more effort into the model to get an end product that you can be proud of. Let's look at some of the options you will face.
The first option you will have to face will depend on when you have purchased a model with or without working doors, hood, and trunk. If you have bought one that is without then do not despair. You still have the option to make the adjustments to the model to add in these features. The first thing you must do is make sure that you have a decent cutting tool handy. A hobby knife is always your best bet. Make sure that you are also able to clearly see the parts you are working on. If you need a magnifying lamp then it is better to use one than to make a mistake that you will have to try to repair. Carefully cut out your doors from the car body. There is no way to avoid losing a little bit of material but as long as you are using a small bladed hobby knife it will be very little.
Once you have the doors cut out then you should make sure that the edges are even so that they will go back almost flush with the body. A bit of fine grit sandwich will accomplish this without removing too much of the plastic. Before you add the doors back to body you need to decide what to use for your hinges. Since you can not add actual door hinges you will have to improve slowly. A small paper clip can be used to create a pair of hinges with just a bit of creativity and work. Now you are ready to add your doors back. If you are painting your model then you should decide whether or not you need to prime the pieces and whether it should be done before assembly or after assembly.
If you are not dealing with much detail in your model car then it would be easier to prime and paint the car after you have assembled it. The adhesive normally used for these model cars actually does not apply well to painted surfaces. If you are going to have a good deal of detail then you will definitely want to use paint before hand so that you can showcase the small details. It is easiest to primer these small pieces before you remove them from their parts tree. You do, however, need to make sure that you either scrape or sand the painted surfaces that will have adhesive added to them so that they will properly hold.