Finished painting the new DIY canopy and the only thing I need to figure out is what type of locking hinge I should use to keep it open when I'm working in the tank
The "stabilus" ones look like the might work out. The first ones might be too strong. Might be best to get them from a brick and mortar so you can take them back if they are too strong/weak.
Canopy looks great, but I would recommend you brace it up with 2x1" on edge or you're likely to see a lot of warping. The front piece looks like it's already going that way. You can use your kreg jig and screw them in from the back, use glue.