Very nice. One wonders why you even bothered to buy a base kit.
I do have a suggestion for the T shaped latches. I posted it the archived site but can’t find it.
Start with Evergreen I beam or H column of the appropriate size. Slice off a thin sliver. Trim to make the T shape and then round the top with a file. It takes about as long to make as it took me to type this, and it looks good.