Please note: I wrote this article some time ago for another site that I used to own. It's not really up to TG standards as it has no images to illustrate it. This is an issue that I hope to rectify as and when I have time to take suitable photographs but in the meantime I offer it here in it's original text only format:
Although models made entirely from brass are unusual outside the genre of railway modelling, brass in the form of photo-etched parts for extra-small details are not uncommon in many genres as is the use of brass extrusion in scratch-building and modifications.
Photo-etched parts may or may not be attached to a 'sprue' depending upon how they have been manufactured. If they are attached to a framework, probably the best was of detaching them is with manicure scissors. As usual when detaching parts from a sprue framework begin by cutting the part from the framework with pieces of sprue still attached. Then, when the part is completely isolated from the framework, remove the remaining pieces of sprue. Note that because of the small size of photo-etched brass parts, tweezers or needle nosed pliers will probably prove useful. Additionally, because of the even smaller size of the off-cuts it is advisable to wear eye protection. The author is inclined to do this kind of work under a desk lamp type magnifier so the lens of the magnifier protects his eyes from flying metal as well as making the job easier. Any remaining cleaning up can be performed with needle files although this is not usually necessary.
Probably the easiest way to cut brass extrusion is with a razor saw although be prepared for the fact that it will dull the blade a lot quicker than plastic or wood. Brass tubing can also be cut with a special tube cutter (if you can find one) that works by holding a cutting wheel against the tube while you rotate it. In either case, some cleaning up with files will probably be required.
Brass sheet and photo-etched parts can be bent using pliers to obtain sharp angles, or bent around an appropriate former to produce curves.
Extrusions can also be bent but with anything other than rod, great care will have to be taken in order to prevent the cross section from distorting. With tubes this can be made less likely by filling them with dry sand before bending.
Brass to brass connections can be made by soldering with 60/40 resin core solder. This is by far the strongest option and is therefore the most appropriate method when extrusion is being used for some kind of structural assembly.
Super glue and epoxy glues/resins can also be used and are probably more appropriate for tiny photo etched parts and connections between the brass and non-solderable metals, plastics and wood.
Full details of how to solder are given in a separate article. Click here read it.
Brass can be painted using practically any kind of paint although it has little texture for the paint to adhere to. Water based paints, such as acrylics, will be much easier to use of the brass is first primed with a coat of oil based paint. In the realms of 'proper' metal working it special "etch-primers" are used which 'bite' into the metal. Unless you model needs to stand up to a lot of handling, you should find that the use of fine wet and dry paper to dull the shiny metal surface (by putting microscopic scratches into it) will give the paint sufficient texture to key to.