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Note 4 - Inventories (Tables)
12 Months Ended
Dec. 31, 2020
Notes Tables  
Schedule of Inventory, Current [Table Text Block]
Inventories consist of:
               
   
2020
   
2019
 
                 
Raw materials
  $
928,221
    $
1,281,250
 
Work-in-process
   
195,618
     
428,463
 
Inventories
  $
1,123,839
    $
1,709,713