One thing that might make the combining stage of crafting less carpal-tunnel-inducing is to make sure every component that is used in quantities over 1 can be equipped in that quantity in someone's hands. That way we can make shortcuts to sort the component into small stacks of the size we need. For example, here's the shortcut I use for sorting iron ore and coal lumps into the right sized stacks for smelting:
/dequip lefthand
/dequip righthand
/equip 2 lefthand coal lump
/equip 8 righthand iron ore
I just put stacks of iron and coal in the first inventory slots and hit the shortcut until the stacks run out and I'm left with stacks of 2 coal and 8 iron. That makes it really easy to Ctrl-click them into the furnace.
Now, for most metallurgy and smithing components we can already do that, but there are some notable exceptions. The rings we use for making chainmail can only be equipped to the hand slots one at a time, and there are a lot of combines needed to make one suit of chain. The various patterns the rings turn into are another example. I can't think of any others off the top of my head, but I'm sure other people can think of some.
