There are two ways to having a sandbox mode
The Online Easiest & Most Convenient Method
Simply visit http://en.uesp.net/wiki/Special:EsoBuildEditor and you can start building your character and fine tune the attributes, sets, skills, CP and other metrics you wish to adjust
It is very easy and convenient, but expect a slight difference from the real game in terms of the numbers
Note: If you only need to play with how Health/Magicka/Stamina and Weapons/Spell damage affects a Skill, you only need to visit http://en.uesp.net/wiki/Special:EsoSkills.
The Slow but Accurate Method
You can play on the Public Test Server (PTS)
Get access to unlimited gold, crowns and golded pieces of ALL sets (including monster/trial/maelstrom sets) in the game!
You even get access to DLCs (Except chapters)
You’ll need to create a new character but it’ll be fully levelled up to max CP for you. There will be a dropdown in the new character screen top left corner and it will be carrying the goodies when you start playing it
The main catch is that the PTS resets every once in a while and that it requires 60+ GB of space, and there are many other small catches such as being a test ground for changes and very few players playing on it
In fact, you can even purchase anything from the crown store for free while playing in the PTS. Except for crown crates and ESO Plus
Do note that it will take up about 60GB of space.
The figures in the PTS may not still match the real ingame figures since it is a testing ground for game changes.
Why aren’t there any Rubedite Ingots / Sanded Ruby Ash / CP160 mats in my inventory?
You’ll need to empty the entire container as the list view only shows a limited number of items
I need a item only with a specific trait. There’s only Divines!
Just Transmute the item. Your character is a Master craftsman!
Unlimited Transmute crystals are available in your inventory
My inventory is too small / horse too slow
Buy horse upgrades in the crown store. It’s FREE on the PTS
I don’t have any character slots left
Buy additional slots in the crown store. It’s FREE on the PTS
I still don’t have any character slots left (maxed out)
Delete a character. It’ll only effect on the PTS.
I can’t find the character I created some time ago
The PTS server does reset every once and then.
Characters are then freshly synced from either NA or EU server
I need more materials / tempers / etc
Start a new character and it’ll be preloaded with goodies as well
Find out how to get started here