Suggestion is to have a crafting level for each player and have that displayed as a state on the player's info page. As you craft different items you level up in crafting. Also, you could have it that if your crafting level is too low than you can't craft high level items but some players may not like this. Optional I guess.

Reference this post:
http://www.spacetimestudios.com/show...Crafting-Level

Thanks to Physiologic for additional input:
"let's say you have to craft x amount of objects y amount of times to increase your craft level, and then you'll be able to unlock bigger and better things to craft!"