Note 7. Line of credit (Details) - USD ($)	3 Months Ended		6 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Jun. 30, 2017	Dec. 29, 2016
Line of Credit Facility [Line Items]
Line of credit outstanding	$ 190,000		$ 190,000			$ 250,000
Line of Credit Facility, Periodic Payment, Interest	10,175		20,511	$ 0
Interest Expense	34,562	$ 22,489	$ 68,010	$ 32,802
Line of Credit [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity							$ 250,000
Maximum borrowing capacity (as a percentage of inventory							50.00%
Current annual interest rate (as a percent)			9.25%
Fiscal period used to compute interest			360 days
Collateral monitoring fee (as a percent)			8.50%		0.70%
Collateral monitoring fee in event of default (as a percent)					1.00%
Line of credit outstanding	$ 190,000		$ 190,000			$ 250,000
Prime Rate [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate (as a percent)			5.00%
Variable rate basis (as a percent)			4.25%
Basis spread on variable rate if delinquent (as a percent)			10.00%
Minimum [Member] | Prime Rate [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Current annual interest rate (as a percent)			5.00%