If you tinker, you find yourself needing to make firm but reversible connections. The standard solution is based on a male-female connectors system, and the only tool you need to make such connection is a set of crimping pliers.
These connector systems are based on the principle of a mechanical connection: the bare wire is literally crushed between small overlapping pieces of metal. The friction between the bare-wire and overlapping metal creates a sound electrical connection as well. Creating a proper “crimp” allows the connection to be made and unmade hundreds of times without failure. Moreover, once you become good at crimping, it will take literally 15 seconds to make a connection—in comparison, a solder gun requires 1 minute just to warm up.
There are a variety of crimp standards, but for POWER connections, I find the JST-style connectors are the best because they are keyed so that the connectors cannot be accidentally joined in the wrong way. To make such connections, I must admit that I love the following set of PA-09 crimping pliers, shown here, from a Japanese company that names itself Engineer, Inc.
I own another set of crimpers, the SN-28B, shown here. Although these were slightly cheaper, and even though they tout the ability to perform both crimps at the same time, I prefer the ergonomics of the PA-09. Moreover, because they are designed to perform two crimps at once, the spacing between the first and second crimp forms is too big to handle the JST-style connectors.
The PA-09 can also crimp the very popular .1″ header pins that are used on Arduino boards, etc. Again, the pliers require two crimps. You can see a full list of the types of connectors that the PA-09 can handle. In the US, I purchased mine from the previously reviewed Sparkfun.
In summary: the tool has perfect ergonomics, the material on the grip and the steap is high quality and a pleasure to use, and because it was designed to do one crimp at a time, it is extremely flexible and precise.