Dovetail joints are probably the strongest of woodworking joints, and with the right equipment they are suprisingly easy to make.
The first photo shows the reversed V shaped bit in a router cutting both the tails and the slotsl at the same time.
The second photo shows the results of this cut, still in the jig that positions everything for you. The third shows the tails and slots turned around ready to go together.
The fourth shows the final tight fitting joint.
The jig is simply called a dovetail jig and it works with any routher.