I'm sure some of you are good at building things - I've been doing it for years, and I'm still not "good" at it... but for those of you who can't figure it out, maybe this will help.
I decided to go with a wooden box ATBA with an acrylic viewing panel, similar to many of the ones I've seen here.
I started with measuring, drawing, measuring some more, and coming up with feasible dimensions and features. I played with several lighting ideas (to light the aquarium, not the basking lights), and chose to go with LED tape. I found some on Amazon that was "waterproof" but I was concerned by some reviews that suggested it was poorly made. I decided instead to buy a kit from the local Home Depot, and mount them on the outside of the tank. To do this, I built my box with an overlap to hide the lights around the rim.
This is what comes in the box. They were about $40, and came with a remote control that changes brightness and color.
I built two basic frames with 1x2 pine and pocket screws (if you don't know pocket screws, get you a jig... once you figure out how they work, you want to build everything. For real.) and attached the back sheathing with glue and screws on the corners.
Next, I cut my two side sheets of sheathing, accommodating for the lighting overlap, and attached them with glue and corner screws.
I decided here that I needed more surface area to glue the viewing frame to, and decided to put two 1x2 pine spacers in the front. Because the construction is so light, it doesn't really need the support, but nobody ever complained about a structure being too sturdy. I glued them in place.
I cut four strips of sheathing to make the frame for the viewing panel, and cut the acrylic to fit. A fine tooth circular saw blade did the trick, but don't expect perfect edges unless you score it and break it.
Now was a good time to test the fit onto the tank (carefully... I'm greedy when it comes to waiting for glue to dry).
I dry fit the frame strips onto the box... I was not happy seeing daylight through my sloppy cuts, and corrected them... mostly.
...then I glued them on.
The only other job for tonight is the ramp and tile.
I cut a small piece of acrylic and carefully used a propane torch to soften it up in the middle and bend a ramp. Then I used epoxy putty to attach it to the bottom of a 12x9 tile I bought at the Home Depot.
I also took the test ramp I made the other day and drew lines with silicone to test adhesion. I'm hoping this will be a suitable staircase for my turtle...we shall see.
Unfortunately for my greedy side, I'll have to wait for the glue to dry overnight and paint tomorrow, then wait for the paint to dry before I can attach the acrylic panel and lights. I'll update after I do that!