I took one out and built my house in 2007-2008, so some of the rules may have changed.
I got my loan through BB&T, and I was my own general contractor. At the time, if you agreed to live in the home for 5 years, you could be your own GC without a license. Since the housing market burst, now you have to have a licensed GC to get the loan.
I started out with a $225,000 construction loan. I ended up drawing the blueprints of my house, and took them to an architect to get official drawings. Before getting approved by the bank, I had to take a copy of the blueprints and a signed estimate from a general contractor (my uncle) stating the estimated cost to build the home based upon the blueprints. I was fortunate, that I already owned 7 acres with an average value of $12,000 per acre to use as collateral, so I was able to get by without a down payment. The construction loan had a fixed interest rate that was a couple points higher than the mortgage rates, and was set for a year. During that year's time, I had six draws from the loan that I could use to pay the contractors. The only payments I made during the construction year was the interest on the money that had already been drawn out.
At the end of the years time, or whenever the house was completed (whichever came first) the loan converted to a permanent fixed rate loan. It involved signing some more paperwork, but didnt include additional lawyers fees.
I had a blast building my house, but it was a TON of work. For the better part of a year, I spent every free minute working on it. I'd get home from work around 3:30 and would work until 10pm every night and then all day every weekend. I learned a lot, was able to buy a bunch of awesome power tools, and still built it for less than it would have cost me to hire someone to do it.
That being said, if I had it to do all over again, I'd take the blueprints to someone and pay them to build it.