SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - New Accounting Guidance (Details) - USD ($)	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle
Net sales	$ 18,396,000	$ 16,302,000
Earnings (loss) from operations	(1,268,000)	(389,000)
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle
Net sales	18,469,000	17,395,000
Earnings (loss) from operations	$ (1,280,000)	$ 147,000