So the current crafting rules for 5e, as the book lists, is that crafting produces 5gp of results every day and requires exactly half the materials in cost.
I find this utterly, mind-rottingly dull. Seriously! It's so.. ghastly simplified.
My proposal is thus: Crafting mundane items, for those of us who love our gadget wizards so, is a function of three variables:
Material
Size
Complexity.
Materials * Size = Cost to make
Materials * Complexity = Difficulty of Crafting
Size * Complexity = Time to craft.
These aren't sound numbers. I'm still heavily refining what I've got here. But I think it'd help me get these numbers out in front of people who've had much more experience tinkering with rules rather than just squinting at them in a corner by myself.
I was thinking of having size start at fist-shaped as 1. Something about arm length is 2. Torso is 3. Size of a person is 4. Size of a car would be about 7. I'll have to make a table for it, but this seems a reasonable scale for the intention. It's not an linear measurement, but with just those numbers, you kind of get an eyeball value.
Materials, then, would be two valued. Unfortunately. As much as I'd like to simplify it, something like gold is very malleable and easy to work with, but incredibly expensive, while glass can be the opposite. It makes sense, then, to have a cost-by-size and a difficult-to-work-with.
Wood being 1, clay being 2, steel being 3, something like mithral being 5.
Complexity is also relatively easy to eyeball rules for. Complexity would be all about those sweet modifiers. So something starts at base 1 for being a simple shape.
Maybe +1 for complexity, +2 for moving parts, +4 for anything involving a jeweler or fine parts. Masterwork might go so far as a +5 or +8.
So let's say I wanted to make a gold watch.
Complexity is 8 for using complex, fine and moving parts
Size is 1
Material is gold: 3 for difficulty, and an ascribed market value that I'd figure out if I had the handbook on me. Cost of materials is actually listed canonically, hooray.
8*3 is a difficulty check of 24 to make. Something an NPC artisan could accomplish, or a focused player, but still reasonably high. A fairly solid number for our intent.
8*1, 8, let's call that 8 days to craft. Even though it's only a little fist-sized object, its complexity certainly makes use of that time in the workshop.
Cost would be size * material cost which I'll have to fudge up when I have a handbook on me.
Alright, how about a set of armor for a horse?
Complexity is 3 for using simple moving parts -- the plates for the horse aren't masterfully complex, but they certainly need to move with the horse and rider. This requires joins and hinges.
Size will be 6
Material will be steel, established 3
Difficulty ends up being 3*3 = 9. Something a trained smith can take 10 on. Here we see just how brutal the 'masterwork' +5 would be: It's suddenly more difficult to make than clockwork at 27, but still a perfectly reasonable number for what should be a master's work.
The size multiplied by the complexity, however, is 18 days. 18 days to make simple armor plating for a horse might not be a very real estimate, but to me as a player it feels like a good number for my adventurer. And those look like very reasonable numbers that lead into it.
Anyway, that's my idea for the system so far. Might come back to it when it's not midnight and see if maybe there are some difficulty modifiers you can throw in to cut down on crafting time, at the very least.