Add case files, instructions, and references.

case/usb-extension.obj

@@ -0,0 +1,64 @@
+# Object Export From Tinkercad Server 2015
+
+mtllib obj.mtl
+
+o obj_0
+v 22.378 		-32.248 		0
+v 15.373 		-32.248 		0
+v 15.373 		-45.253 		0
+v 22.378 		-45.253 		0
+v 13.375 		-47.25 		0
+v 13.375 		-30.25 		0
+v 24.375 		-47.25 		0
+v 24.375 		-30.25 		0
+v 22.378 		-45.253 		20
+v 15.373 		-45.253 		20
+v 15.373 		-32.248 		20
+v 22.378 		-32.248 		20
+v 24.375 		-30.25 		20
+v 24.375 		-47.25 		20
+v 13.375 		-47.25 		20
+v 13.375 		-30.25 		20
+# 16 vertices
+
+g group_0_15277357
+
+usemtl color_15277357
+s 0
+
+f 6 	8 	2
+f 4 	7 	3
+f 3 	5 	2
+f 5 	6 	2
+f 5 	3 	7
+f 7 	4 	1
+f 1 	2 	8
+f 7 	1 	8
+f 12 	13 	11
+f 10 	14 	9
+f 8 	13 	14
+f 8 	14 	7
+f 5 	15 	16
+f 5 	16 	6
+f 5 	14 	15
+f 16 	15 	11
+f 10 	11 	15
+f 14 	10 	15
+f 5 	7 	14
+f 16 	11 	13
+f 9 	14 	12
+f 13 	12 	14
+f 9 	4 	3
+f 9 	3 	10
+f 10 	3 	2
+f 10 	2 	11
+f 16 	13 	6
+f 8 	6 	13
+f 12 	1 	4
+f 12 	4 	9
+f 1 	12 	11
+f 1 	11 	2
+# 32 faces
+
+ #end of obj_0
+