Schedule of Segment Reporting Information, by Segment (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018		Mar. 31, 2017	Dec. 31, 2017
Net sales	$ 10,011,641		$ 9,483,327
Depreciation	326,520		303,197
Segment operating profit	1,561,647		1,437,167
Selling and administrative expenses	(676,939)		(680,928)
Interest income	27,080		14,683
Capital expenditures	226,427		177,314
Accounts receivable, net	6,754,505	[1]	6,173,784	$ 5,326,650	[1]
Inventories, net	4,596,678		5,287,442	4,528,100
Property, plant and equipment, net	12,456,860		12,324,675	$ 12,556,953
Other assets	8,798,774		7,956,280
Fastener
Net sales	8,925,099		8,736,188
Depreciation	291,881		269,837
Segment operating profit	1,177,462		1,191,547
Selling and administrative expenses	0		0
Interest income	0		0
Capital expenditures	184,227		174,789
Accounts receivable, net	6,420,410		5,797,234
Inventories, net	3,658,938		4,075,856
Property, plant and equipment, net	10,175,256		10,187,799
Other assets	0		0
Assembly Equipment
Net sales	1,086,542		747,139
Depreciation	27,298		24,390
Segment operating profit	384,185		245,620
Selling and administrative expenses	0		0
Interest income	0		0
Capital expenditures	31,495		2,525
Accounts receivable, net	334,095		376,550
Inventories, net	937,740		1,211,586
Property, plant and equipment, net	1,646,752		1,542,837
Other assets	0		0
Unallocated Corporate
Net sales	0		0
Depreciation	7,341		8,970
Segment operating profit	0		0
Selling and administrative expenses	(676,939)		(680,928)
Interest income	27,080		14,683
Capital expenditures	10,705		0
Accounts receivable, net	0		0
Inventories, net	0		0
Property, plant and equipment, net	634,852		594,039
Other assets	$ 8,798,774		$ 7,956,280

[1] Net of allowance of $140,000.