Note 7 - Rent Obligation (Details Textual)	3 Months Ended
	Mar. 31, 2018 USD ($) ft²	Mar. 31, 2017 USD ($)
Operating Leases, Rent Expense, Total | $	$ 17,244	$ 16,895
Corporate Office, Minnesota [Member]
Lessee Leasing Arrangements Operating Leases Terms of Contract Cancellation	3 years
Area of Real Estate Property	5,773
Corporate Office, Minnesota [Member] | Office Space [Member]
Area of Real Estate Property	2,945
Corporate Office, Minnesota [Member] | Manufacturing Facility [Member]
Area of Real Estate Property	2,828