The first thing that Eisen did to properly work on his stall was create the actual base for it. Since it wouldn't be that big, it could be brought out in one piece now that Fafnir evolved, so he luckily could construct it here and pop it down wherever he could.
For the base, the old man figured it wouldn't necessarily be all that important to choose any special material, although he did try and choose one that was pretty hard, and ended up choosing regular oak. In the end, the base stall wasn't anything special, it was simply a table in a 'U' shape, where the open side would be placed directly up to the Carriage, with some wooden boards around the outside and a 'ring' along the top of the stall where Eisen could hang a few items from.