Measure twice, take a look at your lines, MEASURE AGAIN! then cut.
I've built a custom reptile tank once... and I screwed it up by not measuring it properly. wasted a lot of good wood. ALSO, sketch out a few outlines on graph paper!
would quarterround do the trick. Got skills used to be a frame carpenter and solid surface fabricator. For the top I was going to cut glass to fit across the top evenly and silicone it into place. Just wandering if the glass would bend too much and cause a leak. Just to be safe I will screw a piece of wood across the top.