ConvertToBase.cs

public string ConvertToBase(uint value, char[] characterSet)
{
    var radix = (uint)characterSet.Length;
    var result = string.Empty;
    do
    {
        var remainder = value % radix;
        value = value / radix;
        result = characterSet[remainder] + result;
    } while(value > 0);
    return result;
}