| Note 2 - Summary of Significant Accounting Policies - Concentration of Credit Risk (Details) - Customer Concentration Risk [Member] | 3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
| Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | |
| Revenue Benchmark [Member] | Clarios [Member] | ||||
| Concentration risk | 0.00% | 80.00% | 16.00% | 71.00% | 
| Revenue Benchmark [Member] | P. Kay Metals [Member] | ||||
| Concentration risk | 100.00% | 17.00% | 84.00% | 26.00% | 
| Accounts Receivable [Member] | Clarios [Member] | ||||
| Concentration risk | 0.00% | 100.00% | ||
| Accounts Receivable [Member] | P. Kay Metals [Member] | ||||
| Concentration risk | 0.00% | 0.00% | ||
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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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