I've been looking at the top h-bar gantry and was going to make aluminum panels contour around the outer h-bar end plate:The part with the circle in the center is the h-bar end plate.
Instead, I decided to customize the h-bar end to not need the end-plate, by making the bolt sleeve deeper(more material around bolt) providing more support as shown below:
Here's how it looks assembled without the h-bar end plate:Without the need for the end plate, I can attach the insulation directly to the aluminum rail, simplifying the assembly of the top closure.
While you can't see the lower two gantry wheels in this image, you can see the bolts that are used to fasten in place:
My plan is to finally finish the enclosure this weekend.