Note 5 - Product Warranties - Changes in Accrual for Product Warranties (Details) - USD ($)	3 Months Ended
	Jan. 31, 2020	Jan. 31, 2019
Balance at beginning of period	$ 120,000	$ 180,000
Liabilities accrued for warranties issued during the period	69,549	137,576
Warranty claims and costs paid during the period	(12,743)	(127,838)
Changes in liability for pre-existing warranties during the period	(106,806)	(29,738)
Balance at end of period	$ 70,000	$ 160,000