Yeah, in fact I actually glue the lens into place then after pushing it down with a cotton bud I super glue the clear part into the light so the foil is trapped and then I trim with a blade.
sorry about the quality, these were taken on my phone a while ago but you should get the picture (excuse the pun) lol.
here you can see the foil lens captures the light well. In the picture below the lens caught the light from the flash and appears white, however it is just the metal reflecting the light.
this is a better one but I think you can see the advantage of tin foil lenses, also on plastic parts for the hydraulic parts for the landing gear I have used foil, it is simple and quick, now I just have to work out how to do it to a whole model lol.