如何编码设置可以使得这 12 个 picturebox 的 image 每次都是随机生成 4 组 3 个一样的素材

以下是一个示例代码，可以实现上述功能：

Dim random As New Random() '创建一个随机数生成器
Dim images() As Image = {Image1, Image2, Image3, Image4, Image5, Image6} '存储素材的图片数组
Dim counts(images.Length - 1) As Integer '用来记录每个素材已经被使用的次数

For i As Integer = 0 To 11 '循环处理 12 个 picturebox
    Dim indices() As Integer = {0, 0, 0} '用来存储随机生成的 3 个素材的索引
    For j As Integer = 0 To 2 '循环生成 3 个随机索引
        Dim index As Integer
        Do '生成一个未曾被使用过的索引
            index = random.Next(images.Length)
        Loop While counts(index) >= 4
        indices(j) = index
        counts(index) += 1 '将该素材的使用次数加 1
    Next

    '将 3 个随机素材的图片合并成一张拼图，并设置为当前 picturebox 的 image
    Dim combinedImage As New Bitmap(images(0).Width * 3, images(0).Height)
    Dim graphics As Graphics = Graphics.FromImage(combinedImage)
    For j As Integer = 0 To 2
        graphics.DrawImage(images(indices(j)), j * images(0).Width, 0)
    Next
    PictureBoxes(i).Image = combinedImage
Next

'每次重新开始游戏时，需要将每个素材的使用次数清零
For i As Integer = 0 To counts.Length - 1
    counts(i) = 0
Next