I'm not from the US :) By "self-build", you mean you actually build it yourself? Doesn't the bank require professionals who can present invoices and such?
In Czech republic they do offer self-build mortgages and you dont need any license (up to 150 sqm). Money are released by achieving milestones and inspection from bank, no invoices required.
Most actually go a lot further than that. We're in the process of building right now with a large-ish builder + separate lender. We can't even do the painting ourselves, the mortgage company requires that we hire it out.
I'm short on free time anyway so it's not that big of a deal but finding a lender that would let you do everything is probably a bit tricky.
Finding a contractor who will take a few bucks under the table in exchange for putting their name on the paperwork and checking your work prior to code inspections is not usually that hard.
You are in charge of the build typically you do some of the PM your self and hire contractors to do the heavy lifting - if you have the skills some do bits themselves