Note 4 - Debt (Details Textual) - USD ($)				3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Apr. 23, 2021	Jan. 01, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Due to Related Parties, Noncurrent, Total	$ 1,175,361			$ 1,175,361		$ 1,175,361		$ 1,123,769
Share Price (in dollars per share)			$ 3.32
Flexo Universal [Member]
Long-term Debt, Total	3,000,000			3,000,000		3,000,000
Line of Credit [Member] | Flexo Universal [Member]
Extinguishment of Debt, Amount								260,000
Conversion of Related Party Debt to Equity [Member]
Debt Conversion, Original Debt, Amount			$ 600,000
Debt Conversion, Converted Instrument, Shares Issued (in shares)			181,000
John H Schwan [Member]
Due to Related Parties, Total	1,175,361			1,175,361		1,175,361		1,123,769
Promissory Note [Member] | John H Schwan [Member]
Due to Related Parties, Noncurrent, Total			$ 997,019							$ 1,600,000
Debt Instrument, Interest Rate, Stated Percentage			6.00%
Repayments of Related Party Debt						0			$ 0
Interest Expense, Related Party				17,000	$ 16,000	51,000	$ 48,000
Promissory Note [Member] | Alex Chao [Member]
Due to Related Parties, Noncurrent, Total	$ 166,667			$ 166,667		$ 166,667
Debt Instrument, Interest Rate, Stated Percentage	3.00%			3.00%		3.00%
Line Financial Agreement [Member]
Debt Instrument, Number of Installments for Periodic Payment	48			48		48
Debt Instrument, Periodic Payment, Total	$ 15,234
Debt Instrument, Collateral Monitoring Fee, Percent	4.62%
Debt Instrument, Fee Amount, Percent	1.25%			1.25%		1.25%
Debt Instrument, Extension Term (Year)	1 year
Debt Instrument, Renewal Fee, Percent	1.25%			1.25%		1.25%
Debt Instrument, Covenant, Tangible Net Worth	$ 4,000,000
Line Financial Agreement [Member] | Maximum [Member]
Debt Instrument, Covenant, Expenditures Amount	$ 1,000,000
Line Financial Agreement [Member] | Prime Rate [Member]
Debt Instrument, Reference Rate	3.25%			3.25%		3.25%
Debt Instrument, Basis Spread on Variable Rate	1.95%
Three Lines of Credit [Member] | Flexo Universal [Member]
Long-term Line of Credit, Total								$ 260,000
PNC [Member] | PNC Agreements [Member]
Debt Instrument, Interest Rate, Increase (Decrease)						4.00%
Debt Instrument, Forbearance Fee	$ 250,000	$ 1,000,000
Debt Instrument, Increase (Decrease) in Forbearance Fee if Equity Issuance Occurs		(250,000)
Debt Instrument, Forbearance Fee if Equity Issuance Occurs		750,000
Debt Instrument, Increase (Decrease) in Forbearance Fee if Full Cash Payments Received		(500,000)
Debt Instrument, Forbearance Fee if Full Cash Payments Received		250,000
Forbearance Expense				$ 250,000		$ 250,000
PNC [Member] | PNC Agreements [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity		9,000,000
PNC [Member] | PNC Agreements [Member] | Term Loan [Member]
Debt Instrument, Face Amount		6,000,000
Long-term Debt, Total		$ 2,000,000
Line Financial [Member] | Line Financial Agreement [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	6,000,000			6,000,000		6,000,000
Line Financial [Member] | Line Financial Agreement [Member] | Term Loan [Member]
Debt Instrument, Face Amount	$ 731,250			$ 731,250		$ 731,250