After getting my 2012 MX-5 NC, I found that my nomal driving position left my left arm floating above the centre console, unsupported. This got tired after a while and I wished for an armrest. In my Smart Roadster I had a fold down armrest from a VW van. However I could only find one MX-5 NC arm rest, made by Zeta Products in the US.

As you can see above, it's really designed for the LHD market. I suppose that entire centre console is designed for the LHD market and was never changed to suit RHD countries... or it was designed for RHD and never switch around for LHD. Anyway. This armrest doesn't actually cover the area where I would want to rest my elbow, so I had to come up with something else.

I started looking at different armrests on eBay, eventually stumbling across an F30 BMW armrest that looked about right. Here's an example of the RHD armrest for those who may not have seen it before.

Using measurements and an image I made a mock up on paper to try for size and fit.

This seemed about right, so I went looking for a decently priced one for sale, trimmed in black leather. Turns out there aren't any as it's a recent enough part, good ones go for £70+ and truth be told I was never completely happy with this shape and size as it's much longer than the space I had, didn't quite fit around the other parts of the console. Therefore, when an E46 armrest came up in my search results and I saw it was smaller, cheaper and seemed to be a better fit, I was very pleased. This is the shape of a RHD E46 armrest:

I printed another mock-up made from yet another scaled image and was much happier with the fit, so £50 later and some messing around with DHL I have a brand-new looking armrest and a whole chunk of plastic I don't need (it came with the whole mounting bracket). I dismantled mine following an online guide so it looked like the one above. I had already been reading this website which offered a guide for fitting an E46 armrest in an old 8 Series, so the design of base adapter plate was my starting point.

I decided to 3D print my adapter plate and made some slight changes to the design, however when the part was screwed on it looked the business. I would later have to remove a chunk of this plate so it didn't hit the top of the handbrake surround in the Miata, but more on that later.

Meanwhile, I had already been working on an adapter piece that would sit in the cubby and provide the anchor for the whole thing. I started on this immediately after ordering the armrest. While it isn't shown here, I produced two types of adapter. One would sit deeper in the cubby than the other. This one would sit on the top, but the back of the cubby couldn't support it.

So I actually used both pieces and they would ultimately be joined together. Having my Ryobi cordless glue gun was very handy for this.

That was a solid mounting point, however there was a gap between the adapter plate on the armrest and these mounts. I shoved a bit of wood in there for this mock-up photo, which was too thick but let me determine the thickness of the intermediate piece I needed to make.

The piece was made, new holes were drilled through from the bottom and long screws (with hot glue) held it all together. These parts were all printed with 5% infill so there isn't as much material used as you would think, it was much better than trying to work with plywood or MDF for this.

Time for another test fit.

It needs a little extra support under this near side, as it can rock a bit if I put pressure on it with my elbow. I have some dense foam that I can cut for that. The colour also looks way off here but it isn't as noticeable in normal daylight.

Overall I'm really happy with this, it provides the support exactly where I need it. I'm trying to think of a way to produce all four components as one 3D model to offer to others, I'm not completely sure yet as such a thing would probably be larger than most printers can manage. Also it's only really useful for RHD so I'm not sure how many would want it.