The easiest way to create a string of repeated characters:
String.String(Char, Int32) Constructor
Initializes a new instance of the String class to the value indicated by a specified Unicode character repeated a specified number of times.
So, to create a repeating string of “x”s 12 characters long in VB.Net:
Dim myString = New String(“x”c, 12)
[Adapted from: http://www.thinksharp.org/?p=45 ]