It is often very difficult or actually impossible to reach in using fingers to install washers, nuts and bolts during building. Sometimes it helps to use long nosed pliers or 'power off' tweezers, but here is a very useful addition to the tool set.
It comprises a small piece of magnetic strip glued to the end of a sturdy length of wire, for instance from a coat hanger. The two I have made use brazing wire as they are non magnetic so the reverse end can be used to move washers and nuts around without them being attracted or stuck to the end of the wire.
The following pictures show how to make this tool. A magnetic strip (which was bought from Hobbycraft) and ¼inch (5 or 6 mm) square cut from it. This is then trimmed into a small rough circle with a knife.
The length of wire (I used about 8 inches or 20cm, but any length can be used depending on your need) is flattened at one end using a hammer.
After cleaning the flattened end the non magnetic side of the piece of magnetic strip is glued to the flattened end of the wire.
I originally use Epoxy resin as the glue but found that this made the end bulky which restricted the access to tight places when fitting a nut. I now use a dab of Superglue directly on the wire and just position the magnet on top.
The whole thing takes just 20 minutes to make and is ready for use immediately afterwards. The wire can be bent into any useful shape to suit needs. I have found that a single kink near the magnet is the most useful.
A video showing how to use this tool can be seen on YouTube. The example shown is illustrative only as this nut had to be readily accessible so the camera could get near to it. In reality this tool can install washers and nuts in very tight and distant places.
Of course, after installing the nut, the next problem is getting the spanner on it for tightening which is a whole new issue!