Another RPG thread, another opportunity to rave about Arcanum, which had a crafting system.
In Arcanum it was simple; just as in some games you can apply points earned by levelling up to schools of magic, so too could you apply points to schools of crafting and science.
There were eight schools; Herbology, Chemistry, Electrical, Explosives, Gun Smithy, Mechanical, Smithy, and Therapeutics. Each of these schools had seven 'levels' of objects to craft, so (for example) if you wanted to learn the third craftable in Explosives you had to learn the two before.
Each school and each level of crafting was also accompanied by a stat check of the core stats, and these stats were not unversally shared between all the schools. So, for example, if you wishes to persue a line of Smithy, you wont necessarily have the stats to persue a school of Herbology. One would require Strength while the other would require Intelligence.
This meant that the crafting system was not so much a class of its own, but something to accompany the build of character you chose, to the degree you chose. Lets say you want to be a gunslinging character; maybe you want to dump tons of points into firearms, perception, and all that, and use money to buy ammo and weapons. Or maybe you'll spend some points on other stats and invest in the school of Gun Smithy, which would allow you to craft some powerful weapons early, and some weapons that are not sold at stores.
Tech build could adopt any style of play; maybe you're playing as a brute warrior, so you want to invest in Smithy to make some of those powerful weapons. Maybe you're playing a charismatic and intelligent character who does more talking than fighting, so you might want to look into the school of Herbology and Chemistry to craft healing potions and stat boosters to get you out of tight spots. Maybe you're a theif who'll also persue a school of Explosives, or maybe you'll persue Mechanical and build some mechanised arachnids.
The choice is yours and it only goes as deep as you want it to. Maybe, as a thief, you're not really interested in a full school of Mechanical. Okay, fine. Just learn the first two levels; spike trap and auto skeleton key. Those will be useful.
On top of this the game also displayed a stat level for each school of crafting. The more you learn in one school, the higher the score for that school. You could buy books to boost these school points, so you might end up with a high score in the school of Chemistry, but a score of zero in Gun Smithy because you haven't bothered to learn anything there.
This point system is then taken further, into a Schematics feature. As I said; eight schools of crafting, seven things to craft in each school. But there's more. You can buy, find, and discover schematics for craftable objects that are not learned through normal school progression. Simple read a schematic and bam, its part of your crafting list. However, some schematics cross schools of crafting, and that is where the point system comes in. You might discover a schematic for the mechanised healing arachnid. To build this device not only will you need the appropriate score in Mechanical, but you'll also need a certain score in another school, perhaps Herbology or Therapeutics. Maybe your character is a pro at Mechanical, but sucks at the other. You wont be able to craft this new contraption.
The actual crafting system was very simple; every object you craft required two components, and as long as you had those components and the right score in that school you could craft it. The 'useless objects' thing didnt really apply, as most goods could be crafted from items bought at stores, found in bins, or scattered around the world. The steampunk setting made it so material was plentiful in a logical way. Want to craft that Chepeau of Magnetic Inversion? Head to the clothing store, buy yourself a top hat, and then run across the street to buy some charges (or whatever). Sometimes the parts were more complicated, though always appropriate. In the above example of the medical mechanised arachnid, you need to have crafted a basic mechanised arachnid for use in that schematic. But that's okay, because in order to have the score to build that medical mechanised arachnid your score in the school of Mechanical would allow you to craft the basic mechanised arachnid.
But you know what? As great all this was, it was totally option. You could, very easily, and quite thoroughlly, play through the game multiple times as multiple different class builds and not once, not ever, touch any of the schools of crafting. After all, there were also fifteen schools of magic to learn, each with five spells, and numerous other skills as well.
And that, ladies and gentlemen, is why Arcanum is my favourite RPG of all time.