Obi-Wan’s Episode I lightsaber was canonically his first lightsaber. He built it during his time as a Padawan and then lost it in the duel with Darth Maul on Naboo.
The lightsaber impresses above all with its simplicity. The metal cylinder contains all the important control circuits as well as switches and buttons in the saber head. The black grip breaks up the otherwise smooth, shiny metal design, as does the black pommel.
Screenshots
Behind the Scenes
This video shows how Ewan McGregor chose his lightsaber:
