[Madclicker]

I seldom use plywood for tools. It starts warping from the minute you pull it from the rack. One exception is the router table fences I make out of baltic birch ply. The design I have, combined with the stability of baltic birch makes a good product.

Dimensional wood would be a far third in my choice of materials for tools.

I think mdf is a superior product to make jigs and tools from.