Been needing to get a screen frame for a small window for like the last five years. I decided to try designing/printing one instead of buying a kit. This consists of three pieces.

1- ScreenFrameCorner 2- ScreenFrameRunner 3- ScreenFrameExtender

I'd imagine these wouldn't work well for a large window. Mine was roughly 16 inches by 21 inches. Due to my print bed size I couldn't print a runner long enough to work, so I created the 'Extender.

You'll need a minimum of 4 Corners and 4 Runners, but in my case it took 4 Corners, 8 Runners and 4 Extenders. Print the Corners and Extenders as is, but scale the Runner to whatever length(s) you need. I ended up printing them a little over length and then cutting them to size since it was hard to get an exact measurement to fit my window. I printed in PETG in hopes it would withstand the elements better (than PLA).