Mallets & Sandbag
You don't always have to have a dolly to shape metal; that's where mallets come into play. These cylindrical and conical mallets are made from ultrahigh molecular-weight plastic that will allow us to stretch and form sheetmetal without marring the surface.
When shaping or repairing something, mallets work best with a complementary surface for the metal to be pounded on. One method involves using a hard wooden surface, such a stump, with a hole carved into it to facilitate the shaping. The most common, however, uses a leather sand bag, such as this one from Eastwood. When filled with buckshot, silver sand, or another preferred medium, the mallets themselves will impart the shape.
For demonstration, Sire is going to pound out a simple teardrop shape in a piece of sheetmetal. The pointed side of the conical mallets is used to rough in the shape. Choosing the mallet size is pure preference, though as with any other hammer, the larger ones offer more mass to swing and will impart more shape quickly. The smaller ones are for more subtle work.
If your swings aren't very accurate, sometimes it works in your favor to hold the conical mallet in place and tap it with one of the cylindrical mallets. Sire also recommends this method for tight spots, or in this case, to get the very tip of the teardrop shape formed.
The impact from the pointed side of the mallet moves a lot of metal, but leaves behind a very rough surface. Flipping it over to the domed side allows Sire to begin working out those craters to create a more fluid shape. All this pounding is bound to buckle the sheet around the edges; the correct way to solve this problem would be with a set of shrinkers/stretchers (which we'll introduce to you in another article), but the hammer and dolly will work as well.
Within about 10 minutes Sire had created this small teardrop with about 1 inch of maximum depth. It needs a little more hammering and planishing to be very smooth, but the hard work is done. A small shape like this is ideal for solving clearance in tight areas; make a much bigger one and you've got the basis for a '64 Fairlane Thunderbolt-style hoodscoop.
What about those cylindrical mallets? Besides just basic pounding, they're perfect for creating shape in sheetmetal over bucks or forms without marring or stretching the metal. For example, that repair panel we adjusted earlier with the hammer and dolly needs a rolled edge. To create, Sire clamped a length of DOM tube into a vise and used a heavy mallet to roll the edge of the sheet to the same contour as the tube. Using similar methods and larger forms, you can create just about any shape imaginable. Now just think of the sheetmetal problems you can solve just by hitting it!
Special Use Dollies
With a few obvious exceptions, such as forming sharp edges, the first thing to know about dollies is that really there is no such thing as the one "right" dolly for a job. Dollies are different shapes purely to help metal shapers and bodymen get it in the right place to work the metal into the right shape. Sometimes a common rail or heel-style dolly will handle everything, but there are times when more curvature may be to your advantage such as is the case with this '69 Mustang taillight panel. The shape of the Curved or Apostrophe dolly is designed for auto body repair and is almost a perfect match for the arc and allows for more precise hammering of some minor imperfections created by impacts from items inside the trunk.
This toe dolly with the raised serrations, and its complementary hammer, are both used for shrinking metal. Metal is fluid and the purpose of the serrations is to gather the metal in an area by creating a series of tiny divots. This method is only for small amounts of shrinking and works well on areas of metal that have been over stretched or "oil canned." There are a couple different types on the market, but the type that do work the most effectively are quite sharp with a grid of tiny, sharp pyramids (rather than flat-topped serrations), such as both of these Fairmount tools.