Originally Posted by
RickAllison
Crafting very much depends on DM buy-in to be effective. For just making any mundane thing, you just need the tool proficiency to make it, money, and time. To make magic items, you need the tool proficiency, time, money, an exotic material, and you need to know how to make it.
Tool proficiency: This one is fairly straightforward. If you want to make armor, you need smithing proficiency. If you want to make a wand, woodcarver's tools proficiency. Herbalism for potions.
Time: For mundane items, it takes a day's work (8 hours) for every 10 gp of the cost (it takes a while to craft plate armor). For magic items, this depends on rarity. 5 days for common, 10 for uncommon, 50 for rare, 125 for very rare, and 250 for legendary, with halved time for consumables and special rules for potions and scrolls.
Money: For mundane, it takes half of the item's cost to make it. For magic items, it's 50 for common, 200 for uncommon, 2000 for rare, 20,000 for very rare, and 100,000 for legendary, halved for consumables and with potions and scrolls working differently.
Exotic Material: This is why magic items can't be mass-produced. You need some special item that can only be obtained by overcoming a CR X encounter. CR 1+ for common, 4+ for uncommon, 9+ for rare, 13+ for very rare, and 19+ for legendary. A skin of a regular Yeti could be used to make a common item which keeps you feeling cozy (mostly RP, but could possibly give advantage in cold weather), while that of an Abominable Yeti could be used to make a true Ring or Armor of Cold Resistance. It could also be something that is guarded by a challenge of suitable CR, like a flower in the feylands. Does not apply to potions or scrolls.
Recipe: Finally, we come to something which does not have actual rules in most published sources, but will be released with Wayfinder's Guide to Eberron. You need a recipe to even start working on the magic item, and these take even more time to make and have minimum skill bonuses required (Arcana for arcane casters, Religion or Nature for appropriate divine). For example, a rare item requires a +6 skill bonus, which for most point-buy characters isn't going to be until level 5. A legendary item requires a +10 bonus, putting it out of reach until high-level play (or for someone with Expertise).
As Damon_Tor noted, Artificers are great for this because, in their specialty, they get halved item cost and quartered item creation time. If a wand of Dancing Lights (presumably common rarity) requires a Will o' the Wisp essence, an Artillerist with the recipe can crank one of those out in ten hours of work and for 25 gp. An alchemist mass-producing basic Potions of Healing can crank one out every two hours for 12.5 gp.
EDIT: Incidentally, my current PC is a Warforged Artificer focused on crafting wands. I play him as very Magitek. He uses a Wand Sheath to fire wands like a super battle droid from Star Wars, most of his spells are fluffed as body modifications using magic to replicate science, and so on. Detect Magic basically is a sonar system, Disguise Self is a holoprojector, and so on.