well, to be honest the middle junction is optional. its mostly there because its a bugger working at the bottom of a tube
In terms of dealing with water ingress, you'd have a few options. depending on how you wanted to handle it. The 'easy' option is to just get happy with gaskets, which are easy enough to cut out of rubber sheet. Gaskets are not super appropriate for the middle joint as you want heat transfer through it. You could also machine lips into each section so the pieces fit into one another, which would also help.
With this build having the mount points in the center, your biggest issue would be with material potentially bowing. Not super likely, but the thinner the end plate material (i assumed 5mm) the more likely it is, especially if you over tighten the bolts. You could redesign it to have mount points in the edges and have less heatsinking without much hassle.
As for light bleed through the front panel, thats a given and theres not a whole lot you can do about it. I personally dont know how you'd protect against water in this design any other way, as you cant trust the optic in that matter, so its gotta be covered. I mean you'll get light bleed across your handlebars, but thats actually somewhat useful.
So what do you think barry, is that a project you'd be interested in having a go at? Or have i inspired a better idea? I'm a do-er, not a talker, so lets get this thing rolling
well to avoid the upward spill you could step the front of the light and recess the front window.
As for making it out of multiple parts i would suggest that i would have enough projection to get down into the hole, but need to check the dimensions. The star is 20mm but the optics are 25mm in diameter. If you can check them out that would be usefull.
I am happy to machine up lights using your designs or something I have already made. I can transfer your drawing to cad to make sure everything will fit. I do not have a cnc but use a manual mill and manual lathe. I can also anodize you parts in red, black, blue, orange, green, yellow, violet, gold or raw.
Here's a few of my latest builds.
Triple XML with h6flex driver
Double XML with h6flex (pre Lflex availability)
Triple XML, same as above but smaller and lighter
triple xpg or xpe
Single XML Manual Focus Aspheric helmet lamp with Lflex driver
Here's my personal thumbs-up for brad72's work. He did a small housing for me earlier this year, and it turned out absolutely great. In addition, he shared some design ideas that made the final result way better. I wouldn't hesitate to work with him again.
I've been meaning to get off my $%# and post a build thread in the lights diy section of mtbr dot com... will post here when that exists.