Depends on the design, the kinds of built-ins you incorporate, and on and on......
Chubby took four months of week end days as it was my first effort at a full sized teardrop. 160 - 200 ?? hours

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I built the barn in exactly 30 days most of this work was done on very long Saturdays and Sundays. So lets say 90 100 hours.

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I had Rip Van Winkle rolling and weather proof in 3 weekends about 60 hours. It took a year on paper but during that time I was derailed building the caboose tiny house and the chuck wagon for the Cross roads of America gathering.

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So with each build I got faster and better and used different techniques to weatherproof the units.
As to money I have never had much to waste and they were built with a great deal of used and recycled lumber and found trailer bargains.
I have to guess a bit on cost but Chubby was about $900.00
The barn about the same and Rip was my bargain at about $300.00.
With a lot of good shopping you can make a very nice little trailer without a giant outlay of cash. Yard sales , Craigslist , and sometimes just walking up and knocking to ask about an item saves big $$$$.. The little trailer that Rip is built on I did just that! I knocked and offered $50.00. It wasn't for sale

so I left a phone number in case things changed. A week later she had polled her grown children and no one wanted dads old trailer so she called and we negotiated to $65.00 and I filled up the flat tires and towed it home.