I’ve been using dot paper (both “square” and isometric) in my grade 9 class lately, so I put together a Java application that generates it. The image files it produces are PNG files. Feel free to use it if it’s helpful. No warranty, expressed or implied, yada-yada.
Here are a couple of PDF examples that I produced from the PNG files:
The PNG files are set to 72dpi, not the desired dpi the user chooses… I haven’t figured out a simple way to set that information in the PNG metadata. The PDF files above are both 600 dpi, if I remember correctly.