Maester
Anyone can make a sword. At its essence it's just a sharp piece of metal with leather wrapped around the bottom after all. But not all swords are equal. One that is forged by an ameteur is a sharp club. One that is forged by a Maester can cut through the dragon scales with ease. A fighter who follows the path of the Maester becomes an expert at crafting the equipment of their comrades and themselves.
Tool User
At 3rd level choose three artisans tools of your choice. You gain proficiency with these tools. In addition, double your proficiency bonus to ability checks using artisan tools.
Expert
Starting at 3rd level you gain a Craft Pool you can use to craft items. You gain a number of craft points at the end of a long rest equal to your fighter level, and can store a maximum number of craft points in your Craft Pool equal to five times your fighter level. Whenever you gain a level, including when you gain this feature at 3rd level, you gain enough points to completely fill your Craft Pool.
You may expend craft points in order to create items without downtime, as long as you are proficient with and use the tools necessary to craft it. One craft point is equivalent to 1gp worth of crafting. By expending a craft point and working for one minute, you can crete an item worth 1gp or less. Alternatively you may put that 1gp towards a larger project. This works the same way as crafting does in down time. Items are not usable until you have fully crafted them, but you can keep an item partially crafted indefinitely.
You can only craft this way if you have materials available. In general however unless it's something ridiculous such as building a wooden boat in a treeless desert it should be assumed you can scrounge up materials from almost anywhere.
You can expend craft points to craft during downtime in addition to any other downtime activities you perform, even if that activity is more crafting.
Master Craftsman
Starting at 7th level you may craft masterwork items instead of regular items whenever you craft. Masterwork items are considered to cost five times as much to craft as their mundane equivalent, with the exception of consumables such as alchemist fire or healer kits which instead cost twice as much.
-Masterwork weapons give the wielder an additional +1 to attack and damage rolls with that weapon, and are considered magic for the purpose of overcoming damage reduction.
-Masterwork armor and shields give the wearer an additional +1 AC.
-Masterwork ammunition does not break when shot.
-Mastwork items that grant advantage on an ability check or a bonus to an ability check grant an additional +2 bonus. This includes tools.
-Masterwork items that would cause the enemy to make a saving throw or ability check grants the enemy disadvantage on that throw or check.
-Masterwork items that would heal or deal damage heal or deal twice that amount of damage.
-All masterwork items are five times as hard to break as normal.
You may upgrade an existing item to a masterwork version by crafting the difference between its base cost and masterwork cost.
Dilettante
Starting at 10th level you may craft items without proficiency with the tools necessary to do so. You cannot craft mastwork items in this way. You still need to use the right tool to craft the item, even though you aren't proficient with them.
Rapid Crafting
Starting at 10th level you craft much faster than normal. When crafting using a tool with which you are proficient, you may craft 2gp worth of item(s) for every 1gp or craft point of time you spend.
In addition, you may spend gp instead of craft points when crafting. When doing so you do not gain the benefits of the rest of your Rapid Crafting ability, but by spending a gp and a minute of work you can instantly craft 1gp worth of equipment. You may only use this ability while in a settlement.
True Maester
At 15th level you a paragon among craftmen. You may craft masterwork items without having to be proficient in the tool necessary to make them. You may also craft transcendent items, as long as you have the necessary tools to craft the item and are proficient with them. Transcedent items cost five times as much as their masterwork equivalent.
-Transcendent weapons give the wielder an additional +3 to attack and damage rolls with that weapon, and are considered magic for the purpose of overcoming damage reduction.
-Transcendent armor and sheilds give the wearer an additional +2 AC.
-Transcendent ammunition does not break when shot, and can be reclaimed after every battle even if doing so would normally be impossible.
-Transendent items that grant advantage on an ability check or a bonus to an ability check grant an additional +5 bonus. This includes tools.
-Transcendent items that would cause the enemy to make a saving throw or ability check forces the enemy to make that roll with disadvantage. This disadvantage cannot be cancelled by advantage.
-Transcendent items that would heal or deal damage heal or deal five times that amount of damage.
-All transcdent items are indestructible by anything less than spells of 9th level or higher, the supernatural abilities of creature of a CR of at least 16, being crushed by a creature of 30 or more strength, or adamantine.
You may upgrade a masterwork item to a transcendent item by crafting the difference between its masterwork cost and its transcendent cost.