Looking for sound advice

[PixelsnPrint]

I'm totally new to all this machine design and concept of building a CNC router but here's my thoughts and concepts, not to mention questions. First the media I plan to cut/route typically would be MDF, UDF, Acrylic, Sintra board; basically your typical sign building components. Working envelope either 48"x48"x6" or 48"x96"x6", I'm designing and budgeting for the larger one but will resize if figures get away from me. Here are a couple key questions, One given material options for constructing the gantry and it's support structure from should I use MDF or Corian both are wood working tool compatible and require no special skills I do not already have. attached is a pdf of my concepts granted x-y-z cars are not complicated designs but should suffice for my cutting needs. Please advise as to thoughts and suggestions.

Thanks in advance,
Richard Morton