Paul, you should check out the crafting system in 7daystodie. Actually you should play the game for homework to see what they have made work and what you dont like about their engine. They have put a whole lot of work into it since their kickstarter ended.
http://7daystodie.com/Someone pointed me to this game before. I kind of despise zombie games at this point and don't have that much money for games these days. I limit my game spending to games I can play with my son or games that I really really want to play. This doesn't look like it falls into either category unfortunately.
I went to the wiki and the crafting looks like it's recipe-based. So put n random ingredients in, get something else out. Is there more to it than that?
I also saw that block making kind of seems to work this way, too. Like x pieces of plywood and you can make a shingles block or whatever. For blocks, Mythruna will work something like that someday. If you have the raw materials and know the skill then you can make these non-elemental blocks like shingles, W&D, etc.. Your build wand will let you manipulate raw materials but to learn to combine them will require skills. This may be one case where I allow self-learning to some extent... where if you suck up enough of a particular block type then maybe you can learn it. But it's been a long week and that may be crazy talk.