What Are They?
Grand Master Crafting Stations (formerly referred to as "Durable Stations") are unique crafting stations introduced in Update 40 for The Elder Scrolls Online that will allow players to deposit any Attunable Crafting Station (crafting stations that allow crafted Item Sets to be crafted in a player's home) into their respective Grand Master Crafting Station (Woodworking, Jewelry, Blacksmithing or Clothing).
The new crafting stations means that instead of having rows and rows of 308 Attunable Crafting Stations (4 crafting stations per Item Set) in a designated "guild hall" taking up 308 furnishing slots, homes will see only 4 equipment Grand Master Crafting Stations.
How To Get Them
You can purchase Grand Master Crafting Stations from Faustina Curio (Writ Voucher Vendor) located in Mournhold, Wayrest and Elden Root for 1,500 Writ Vouchers each (you earn Writ Vouchers from doing Master Writs).
How To Prepare and Use Them
Once you are in your home or 'guild hall', you can set the Grand Master Crafting Stations down and you must retrieve all of your Attunable Crafting Stations into your Inventory and then approach each respective Grand Master Crafting Station to add or "deposit" each Attunable into it.
Note that this permanently removes your Attunable Crafting Stations but the data is saved in your Grand Master Crafting Stations allowing you to craft any of the item sets added in your home.
What Happens If You Destroy Them?
It is highly recommended you DO NOT destroy your Grand Master Crafting Stations once you add any or all Attunable Crafting Stations to them as you CANNOT recover the Attunable Crafting Stations and you must essentially start all over again by purchasing Attunable Crafting Stations, attuning them to the Item Set locations in overland and then putting them again into your new Grand Master Crafting Stations.