I broke my side panel of PC build with a simple touch to a metal part of the case. I believe someone can encounter the same problem.

I made a top-left quarter with a window. Some transparent plastic can be places from the rear side with a hot-melt adhesive. You can use alternative enclosed version. It also recommended to stick panels not only with dowels, but with some glue or adhesive.

Feel free to adjust models to fit your PC case and holes. You also can modify center plate to add some pattern like on my photo. I left it for you.