Corian Directional and Stairwell Signs

[John Bion]

Hi Keith,
Thanks you for your detailed reply, I appreciate your advice.
I am just a little confused (others may say I am a very 'confused person') over two things:
1) What is the advantage to machining down the Corian thickness? Will it warp in weather exposed environments in a machined down form?
2) I think I understand what you mean about machining 3/8” holes for masonry walls, but if you would post a picture of this, that would be great I see how this would aid in locating the screw, however I am not sure how it would help the screw into the 5/16” slot if the screw is a little misaligned in the wall.
I’m off to locate that bit now...
Thanks again and kind regards, John

Edit: would 2 flute spirals be the correct cutting tool for Corian? Thanks