Custom-fit
This achievement easily takes 5-10 minutes if you have the right amount of materials.
In order for you to make items, you need crafting materials. To obtain crafting materials you take any item go to the blacksmith, hit RB to the salvage part, then you can salvage any items.
The cheapest and fastest item to make is the Apprentice boots it requires 5 Exquisite Essence, so if you have 500 Exquisite Essence you can obtain this achievement without even worrying.
Another thing you can do if you don't have 500 Essence is make as many as you can then salvage them again to get back some or most of the Essence.
Just make this 1 item 100 times and the achievement is yours.
Any questions or concerns? Message or comment! Good luck, have fun!