Hi jjensen and Welcome to the Forums!

In reading your post I am not really sure what you are trying to do. It sounds to me like you are trying to create a block library, add png files so that you can use the CUI to create a custom partial menu. Is this correct?

If so, I recommend keeping your library in a separate folder and simply adding it to your Support File Path. You can even add PNG files here if you like. You do not necessarily need to put the image files into a DLL.

If I am understanding your question correctly, please update your post so that I can provide additional resources. Otherwise, let me know what else you are trying to do.

Please hit the Accept as Solution button if my post fully solves your issue or answers your question.