I know that Portal is not anime but...
In addition to FMA and Tenchi Muyo, I'm also considering getting an orange jumpsuit and building a life-size companion cube to replace my own head.
I could even make a portal gun.
I need to make a few prototypes of the cube tho before I commit to this.
Any other suggestions?
Perhaps a cake....
I could easily make a real cake but it wouldn't last long on account of my friends raiding it while I wander the con.
But a prop cake would be apropros.
"The cake is a lie!"