First of all, thanks for making such a nice mod, and sorry for my bad English.
I was trying to make a metal casing for macerator, but I was not able to make one because it doesnt shows in craft screen.
I tried to find out if I haven't learn the recipe, but I've already read the Welding Textbook which teaches how to make metal casing.
So I looked into script file if there is any glitch in there and I've found whats wrong.
It was In Book.txt file,
TeachedRecipes = Build Industrial Furnace;Cut Steel Pipe;Cut Sheet Of Metal;Make Large Sheet Of Metal;Make Metal Pipe;Make Steel Beam;Make Metal Barrel;Make Propane Tank;Metal Casing;Weld Punching Bag Stand;Weld Weight Bench;Repair Treadmill;Make Dissection Table;Make Metal Wheels;Make Pulley;Make Mine Cart;Make Chain;Construct Barbed Wire Barricade;Construct Concertina Wire Barricade,
Its missing a word 'Make'. So I put the word in it and everything works just fine.
I just wanted to help you little.