Transparency film for a washer, eh? I like it. I may have to steal that idea!
It looks like on your tray, the issue was the extension goes UP instead of dropping down (since it's flipped). Is that correct? Minor issue, since a sliver of a spacer apparently fixed it, but just to be clear, that's what the issue was, right?
That's a huge rig for such a tiny camera! LOL
The extension was never an issue. Instead, I was pleased to note that the housing's bottom corner is cut in under the door lock to the right height for the ULCS extension.
No, the issue was that the bottom edge of the housing's door would scrape across the main part of the tray when it opened or closed. The door and the housing body were milled exactly the same size. So, when the housing was screwed onto the tray, the door was pressed up against the tray as well.
Yes, it is a big rig for such a tiny camera. I started with Olympus UFL-1 and needed two of them to get any coverage at all. I went with ULCS arms so I could upgrade to a dSLR housing later. Well, the S90/FIX came by and I could not resist it. So, I decided to postpone my dSLR housing a bit longer. This camera is very impressive for wide angle work. I am not so happy with its macro yet. I need to get a macro wet lens for it, but have to wait for others to figure out what WA/macro lenses work best. Hopefully the answer comes soon as I have a nudibranch trip to the Channel Islands in a month.