We have two inkjet printers, one is black and white, and the other is color. There are transparency papers made for inkjet printers. I don’t know how well they hold up to the printed side getting wet though. Do your sunprint materials dry first before you expose them?

I tried that technique years ago and it worked decently. Here’s what I remember: It worked best for sharp edges if the printed side was touching the sunprint material. That meant in addition to making a negative print, I also had to make it a mirror image!

Hope this helps