Condensed Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities:
Net income (loss)	$ (1,121,118)	$ 358,878
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	78,203	97,990
Amortization of right-of-use assets	120,902	0
Stock based compensation	175,012	33,798
Provision for (recovery of) accounts receivable allowances	1,943	(185)
Provision for inventory reserves	23,957	0
Changes in operating assets and liabilities:
Accounts receivable	(430,021)	(606,421)
Inventories	1,421,071	(177,628)
Prepaid expenses and other assets	312,542	(487,067)
Operating lease liabilities	(129,831)	0
Accounts payable and accrued expenses	(713,268)	920,752
Net cash provided by (used in) operating activities	(260,608)	140,117
Investing activities:
Cost of other assets	(135,000)	(40,000)
Purchases of plant and equipment	0	(18,905)
Net cash provided by (used in) investing activities	(135,000)	(58,905)
Financing activities:
Net proceeds from (payments to) bank credit lines	380,112	(39,707)
Proceeds from stock option exercises	5,100	152,463
Net cash provided by (used in) financing activities	385,212	112,756
Net change in cash	(10,396)	193,968
Cash and cash equivalents at beginning of period	125,982	229,218
Cash and cash equivalents at end of period	115,586	423,186
Supplemental disclosures of cash flow information:
Cash paid during the period for: Interest	32,217	6,168
Cash paid during the period for: Income taxes	$ 7,788	$ 3,598