Hi folks,
I'll keep it brief: I'd be very grateful for an opinion from some of you learned chaps on the cause of the variation in appearance of the attached. This isn't something we've encountered before.
Both of the aluminium parts shown (there are two, call them top and bottom) were supplied...
Personally, I feel that the "skill" most important to my professional development and work is resourcefulness. If you know what you don't know, you'll be ahead of most know-it-alls already. Support that with resourcefulness - knowing where to find the support, information, data, calculations...
What immediately springs to my mind are these. You may have to do a bit of hunting for the right size though. As others suggested, some sort of application would be useful (I know you have an application - I mean, telling us what it is).