It is legal to own and be in possession of a still in South Dakota but it is illegal to use it for anything. Essentially it is purely for decoration or to allow distilleries setup and wait time on licenses. You cannot use the still for water or essential oils without a permit.
I was unable to find any information on fuel alcohol for this state.
South Dakota does offer distilling licenses for Commercial manufacturing. License fee is $4,000 per year.
South Dakota distiller license
There are several licenses you need to request to legally manufacture spirits. Below are the federal licenses only. Additional state requirements will need to be followed as well.
You must submit a request for a license to manufacture spirits: TTB 5110.41 Basic permit.
This license only allows you to produce spirits. You also need a license for the distilling equipment / distillery: TTB 5100.24 Distilled spirit plant
For manufacturing ethanol fuel you will need to submit a request for a TTB 5110.74 for a federal license.
Traffic in alcoholic beverages prohibited except as authorized by title. No person may produce, transport, store, or sell any alcoholic beverage except as authorized under the provisions of this title.
Unlicensed business prohibited--Violation as misdemeanor. No person may transact any business authorized by this title without a license as provided by this title. A violation of this section is a Class 1 misdemeanor.
Current federal laws allow citizens the right to own a still and operate it for non-alcohol production.
This means legally you can: