How can I make a random shape generator using a list?

I want to make a random generator that is based on a grid with two list: A to Z & 1 to 26. Each letter and number will have a different shape in it that is a square. My goal is to make infinte combinations between the letters and the numbers and also have the squares rotate 90 degrees each time. I would also like to save each combination as a vector of jpg file.

Now I think JavaScript is the way to go here, I have worked with it before using html but not using anything else. I'm still a beginner but I think I could make it work.

Here is an example of the grid I'm basing it on: basic grid

If anybody could help me out a bit I would very much appreciate it!