What i'd be looking to do is first can a flexible sheet that flexes and wraps around that hole on the back work? i'm not sure if you're wanting a dome looking thing. Or an after market like those and to fill the hole use some abs plastic cut around the bracket.
My guess is you're thinking some pod looking custom thing.
A flexible sheet that you could put some small circular cutouts for the small circular xenon types? (i dunno i just drive my truck) in would be easy...either glass or plastic. If you're wanting like a pod looking thing that's going to be some work.
Easiest I'd be thinking diy vac forming, i've done some marine radio, chartplotter,etc faceplate covers that way but didn't get too far into it....i'm not knowledgable on the types of plastics and how heavy of a plastic you can do it at home. The stuff i made was thin, but easy just made a wood buck and vac'd over it. Had to make a diy vac setup with a shop vac, some wood frames, bolts, nuts,etc. my guess is that will be too lightweight.
With glass you have to make a buck to make a mold from (you glass the buck, then use that for the mold since the inside is now smooth...little to no fairing except you get out what work you put into the buck). Or you make a mold glass over it and do the tough way of fairing everything ..That gets old quick!
...but then again some do spend tons of time doing that for stereo install and such. On something like that though i mean it's not a ton of work. Heck if i wanted it i'd probably do it that way. It's no different than how they glass up those stereo box installs and stuff.
Or you can make a reverse mold, those come out pretty good, i've done boat hatches and such that way. Again how much work after is due to how much work you put into the mold.
BUT if you can say take a flat sheet that has some give, cut it out, and cut some circulars in there and bolt it somehow that will be tons easier. ABS will be cheaper... or roll out some glass on a piece of glass or melanine and you'll have a heavy duty piece of glass as smooth as a babys **** that can flex.
You could possibly combine the two, make a buck from some thin ply, cut some wood domes there (which you'll eventually cut through after you pull the mold) glass over that. do some quick smoothing and some run of the mill canned high build primer. Probably come out pretty decent. Attaching it may be a pain figuring out.
Epoxy is expensive, i have this bad habbit of picking up boats and having to do transoms and decks . 75 bucks a gallon from a fiberglass supply then you have shipping....WAY too much resin for this project. polyester resin much cheaper, comes in smaller quantities, with some matt glass. Probably all you need there...you're probably talking 30 bucks then some rattlecan high build primer and paint. polyester is styrene based it smells like heck, your wife kids will complain endlessly.
You won't get the itches from this, only when you probably use an angle grinder or dremel to cut whatever you made out..that's a small project. Do a transom or deck replacement THEN you'll know the itches!
I'm not a pro! my projects are amateur....just diy but here's some pics to give you an idea ...one is my first test vac forming for a radio cover on a boat, another i made a windscreen hatch from a buck but i didn't use that for a mold it was tons of fairing, another a door. Anyway long story ...never liked deck bow riders that stuff, decided i only liked center console fishing boats after that and am working on that now.
tons of googling you should be able to (quicker and tons easier though if you buy it!)
