ok, so im no carpenter and probably could have taken a little more time, but you know, i rarely use a router, and proberly had the wrong cutting bit, but hey ho, heres my go at adaptor rings, that a knocked up in literly an hour
so these are 6" speakers to fit in to the original location, the vibes have a shallow mount and including 10mm mdf produde about 20/25mm more then original location
i did try and do a pod mount which turned out good, but kept hitting my foot, and just looked gash from a oem standpoint.
adaptor ring, i cut about 1/3 way down to allow movment of cone and it sits nice and centred
then had to cut a slot becasue theres no other way to do it and get it right in to the corner to clear the door skin.
i decided id go all bodge and use some masking tape and tape the out side and fill the inner side with thin packing foam (the stuff wrapped round games consoles and such)
so once set in place i run some resin around the foam to make it go ridged, hold ot in place with the attempt to direct the sound out and not in to the back of the card
and then with the foam back over you can see it still fits in the foam. all good.
lastly if you want me to knock you some up give me a pm, and i promise to take more care with the cuts. i just did it as a spur of the moment boeardem type deal. but they came out really good. and i found why my door speakers were crap, the foam pretty much all the way round had seperated from the cone!
hope you enjoyed that and give you some ideas of your own.