I was wondering how I would go about setting up a set of leather, wooden or hide or some other non-metal armour for a druid character where the armour changes shape when in beast form so that it is always present, sort of like a normal armour that can change to barding so it always fits the wearer. The armour is intended for a druid character to allow for the use of armour in beast form without requiring another character put barding onto the beast form druid as that would take up valuable time, limiting the time allowed for beast form if the druid wanted to be an armoured wolf. any ideas would be appreciated
There are no rules for this
If you're the DM then... make it up (homebrew it).
I would use the rules in the DMG chapter 9 (p. 284) to make a magic item that when attuned to a druid gives them the bonuses of leather/wooden/hide armour and changes shape when the druid goes into beast form. This would probably be a rare item (possibly higher but no lower) because it would give roughly +2 to AC but when you make it you can look into it more.
If not then ask.. but be prepared for a no.
Not all DM's want to homebrew. That's just a fact of DMing if they say no take it graciously and still think about how druids are still fairly powerful without special magical armour.
Multiclassing can give you this effect (if not this equipment)
It is ambiguous whether standard magical armor will reshape itself to a Wild Shaped Druid instantly, or if it will only fit to the Druid's natural humanoid shape. As such, there are no clear rules that provide the equipment you are hoping for.
But you could gain the benefit of leather armor while in Wild Shaped form through multiclassing or Feats. For example, if you took one level of Monk and had a wisdom score of 14 or higher, your AC could always be at least 12+Dex Modifier in any beast form, due to your Unarmored Defense (which, as a class feature, would remain in effect while Wild Shaped). Or you could take a single level of Wizard and cast Mage Armor on yourself before changing into a beast, making your AC at least 13+Dex Modifier for several hours. The Feat Magic Initiate would also permit you to use Mage Armor in this way.