A nice modification that you also see a lot with BMWs, Volkswagens and Peugeots are the Angel Eyes or a ring of light around the headlights. As a gimmick, that seemed like a nice idea on the MX. That was just an idea until I heard that the headlights of a Volkswagen Golf Type I have the same dimensions as those of an MX-5 / Miata.
The proof of the pudding is in the eating. So I ordered a set of Angel Eyes for the Golf on a web store. Once they came in, of course, it appeared some work would benecessary to make it fit. The Golf has another fitting ring and different adjusters.

First I removed the old headlight and measured everything. What goes where (and why)? And what had to be changed or made new? Luckily the new headlights are fairly universal and a new set of back plates should be sufficient.
So I  got on my computer and made myself a CAD drawing.
(adapter-plates *.pdf file, A3-format)
'Trouble' with this drawing is that it is only for MX-5 fitted with height adjustment, and only for thís specific type of Angeleyes. Miata's and MX-5 outside of Germany have a different fitting which causes this to, well, not fit quite as right. Well... maybe I'll sort that in the future...

After a little squabble with the supplier I finally recieved my new backing plates. Everything fitted nicely:

The new adapter-plates fitted to the lamps. The old brace to the side (to the right) and the other set left.

First I took off the side indicators to tie in the wiring to the halos:

Used my multimeter to find which wire is to the parking lights (in my case the red-black) and which is ground (the green). ALWAYS check your own! These are aftermarket and different suppliers may use different colours.

And then over to the car. The wiring from the indicators led from below to the back and then, following the original wiring to the headlight back to the front:

And from the back:

I tied it to the original wiring with a cable binder to prevent it becoming trapped between the end-stop of the headlight frame:

The new headlight, with the new backing-plates in the frame:

First test:

Adding low beam:

Everything works? Great, then we can fit the streamline covers again:

Almost a shame you can't see anything of it during the daytime....

One more picture at night: