In the early R&C races for sports cars and coupes, most of the available bodies were close to scale - which is to say they were narrow - well under the three inches allowed by the rules.
Those same R&C rules also required the front wheels remain inside the body and not be visible from the top, where the rear tires could extend past the body by 1/16" on each side. Nevertheless, if the body you wanted to use was only 2-3/4" wide, this still won't get you to the three inches you are allowed.
In 1966, you didn't just chuck the body and find a different one that "fit" better (mostly because there weren't any!) instead you made what you had work. One of the ways builders coped with this situation was to flare the fender wells to make the body wider. How this was done has become one of the "lost arts" of building early slot racing cars.
At this point I must admit I've never actually done this! But I do remember reading that builders would literally tie an old teaspoon (using metal - perhaps copper - wire) to a small soldering iron with the tip of the iron inside the bowl of the spoon to heat it up just enough to use this whole contraption to soften and form the edges of the wheel wells into a flared shape (very clever!)
Amongst all of the SlotBlog members out there, surely there are a few who have experience with this "lost art" and could explain how they did it for the benefit of those of us who would like to replicate this practice for our R&C builds.
If you've done any fender flaring in the past, and you remember how you did it, please tell us!