Sam had somehow obtained a vasty piano-box and a quantity of lumber, and, summoning Penrod Schofield and the coloured brethren, Herman and Verman, he expounded to them his building-plans and offered them shares and benefits in the institution he proposed to found.

Acceptance was enthusiastic; straightway the assembly became a union of carpenters all of one mind, and ten days saw the shack not completed but comprehensible.

Anybody could tell, by that time, that it was intended for a shack.
There was a door on leather hinges; it drooped, perhaps, but it was a door.

There was a window--not a glass one, but, at least, it could be "looked out of", as Sam said.

There was a chimney made of stovepipe, though that was merely decorative, because the cooking was done out of doors in an underground "furnace" that the boys excavated.