I will add mine once I go thtrough them too.
--Original message follows--
The following are items that cannot be processed using CNC Machine:
> Snow
> Plastic
> Ice
> Wool
> Glass (All types)
> Trap Items (e.g. Trap Sandstone)
> "More Trees" Mod (All types)
> Desert Stone
> "Technic" Mod blocks
> Obsidian Block
> Gold Block
> Tin Block
> Copper Block
@ Adventurer: I haven't tried using clay blocks...