If I get some time, I will post a blog on building this but wanted to share real quick right now.

This is what I finally came up with. Holds the board pretty securely. I added the piece of paint stirrer to help protect the bit from being damaged on the metal clamp.

I milled a pocket in the MDF so that acts as a barrier on two sides. The clamp presses on the board into the MDF . I thought I was going to have to add a clamp along the x axis at the top but I don't think it is going to be needed.

 

I milled a pocket in the MDF ...

Interesting choice. I would have just added strips of another layer of thinner stock. But I guess you have more options when you have a CNC router.