What are the requirements for obtaining a marital visa in Thailand?

IF you are on a yearly extension based on employment from the immigration office (NOT on a year-long, multi-entry Non-B that you bounce in and out of the country every 90 days on) you can do this;

Get a letter from your employer stating you want to cancel your extension of stay based on employment to get an extension based on marriage. Take that to the immigration office with the documentation needed to get a yearly extension based on marriage.

The second you cancel the extension based on employment, you apply for a new yearly extension based on marriage to a thai national. Because you're a foreign female marrying a thai male there is NO proof of funds like foreign guys that marry thai women.

All you're doing is changing the reason you're getting an extension of stay for. (from employment to marriage). It will go under consideration for 30 days and then you go back and get the year extension inked into your passport.