This achievement requires you to put enough Attribute Points into an Attribute (Reflexes, Intelligence etc.), then level up a skill within those attributes (Handguns, Crafting etc.) to Level 20. Your skill level is capped by your attribute, so if your Reflexes is 8, then your Handguns level will be capped at 8 as well.
There is currently a glitch to make this really quick. Firstly save up enough attribute points from levelling up so that you can get Technical Ability up to 20. Then make a manual save that you can revert to after so you get back your spent points. Use all your points to get the attribute to 20. We are going to get Crafting to 20.
Now you need to get a beverage, any will do. I used 'Nicola' out of the vending machines. Get one of these and go to a Drop Point (box symbol on the map). Make a save. Now sell your beverage to the Drop Point. Back out of the menu, then hit
at the same time. It may take a couple tries, but you should get the shop screen with a clear background. Now you can just mash
on the beverage and buy it as many times as you want. I bought nearly 1000.
Now go into the backpack and drink one of the beverages. Then hold
on the beverage and it will ask you how many you want to disassemble. Disassemble all of them. What should happen is none of them will be disassembled, but you still get the Crafting XP for disassembly. Now just disassemble over and over until you get enough XP to get 20 on Crafting.