Making T square on CNC router?

I was kicking around the idea of making a larger T square out of aluminum and having it cut on our CNC router here at work. It would likely be about 1/4" thick, 12" T at each side of the body and the body itself be about 36" long. After that I can joint and rip down a piece of hardwood and attach it to the T along the edge as a reference point. Only reason why I'm even thinking about it is because I can get it done for free. Anyone have any thoughts about why this might be a bad idea? The router is accurate to within .002-.003" but that's dimensional, it should be able to hit a 90 degree turn dead on.

I'm wanting a larger T square like this for when I get my track saw and using it to square up cross cuts on sheet goods.

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Making T square on CNC router?