I did something similar with my fog lights... except instead of 3D printing brackets we used some type of hard plastic and cut/sanded it to fit. One of these days I'll update my garage with the details, but in the end it turned out pretty well. I didn't use any sealant though, I just left it open around the edges of the light. You can't tell though because it's all dark behind it anyways.
I also would have to agree with the things said above, I bought the halo/projector ones and I don't think I'll be able to use the projector part in traffic because there's no cutoff on them. This is fine for me but if you really want the function of the fog lights just go OEM.
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View my fuel log 2015 Mirage DE 1.2 manual: 42.7 mpg (US) ... 18.1 km/L ... 5.5 L/100 km ... 51.2 mpg (Imp)