Note 5 - Product Warranties - Changes in Accrual for Product Warranties (Details) - USD ($)	6 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Balance at beginning of period	$ 85,000	$ 120,000
Liabilities accrued for warranties issued during the period	77,122	92,769
Warranty claims and costs paid during the period	(46,271)	(46,389)
Changes in liability for pre-existing warranties during the period	(20,851)	(81,380)
Balance at end of period	$ 95,000	$ 85,000