I built some small rental cabins like that.
I used mostly 'mill ends' that were 14 to 24 inches long.
For floor and roof sheeting I used 1x6, 1x8, 1x10 and 1x12 mill ends cut to 16 inches.
Rafters and floor joists were the old telephone pole cross ties that had once supported colored glass insulators. If I recall they were either 10 or 12 feet in length and about 4x5 inches w/h.
I got those for free when they were being removed along the railroad, glass insulators intact.
The mill ends cost me $10 per pickup bed full when dumped in by the front-end loader at the mill.
It was a time of little cash flow for me.
I rented out those cabins for years and eventually sheeted the exteriors with 2 inch foam board and OSB.
Everybody liked the butcher block appearance interiors.
It'd take a few truckloads to complete a cabin but with nails and rolled roofing included they cost less than 4 or $500 each to construct.
