Well, not a "breakthrough" achievement by any means, but just wanted to share my design for making and fastening a lid to a vertically oriented tank that works great for one of my cresteds and I'm sure would work well for other species too.
Here's what it looks like from the front. A simple frame that is covered on the backside with metal screening.
Here's what the "locking mechanism" looks like. I siliconed two pieces of wood, one on each side of the tank, to anchor the hooks, which latch into the eye holes attached to the frame.
No more buying manufactured petstore screens for tanks that sit vertically due to a lack of a locking mechanism. Works great thus far.
Thanks and Happy Holidays!
-Adam