I design this Palm Arduino (version 3) prototype PCB to be encased by Lego bricks, especially Lego Technic Bricks, for the reason that I was hooked by the Lego after my first Lego project - R/ C Lego Car. And I am working on a couple projects that are using Lego Technic components with Arduino. (I will post instructables as the project is ready to post.)
Also, I want to be able to use Palm Arduino in wide variety fashions. For example I could use either right angle female connectors or straight female connectors. or could use straight power switch or right angle power switch. etc. By doing this, I would facing the challenge of the enclosure designs to fit all of the mentioned criterial, and not very cost effective since we have to make 3D Print for each individual case.
For these reason Lego bricks are the best option to be used as the case of Palm Arduino Version 3.