I bought a spinner from Ali Express, so I made my own enclosure for it.
I'm quite happy with the way it turned out.
It's exactly the same height as my other controller and the same material, so they look like a set.
Initially I messed up with the whole cutter, so I used a metal ring from a ball bearing to cover my mistake.
It ended up looking even better this way!
If anyone is interested in this box, just type "Project Box" on ebay. They come in many sizes. I got the box for £7.
I decided to not attach it with screws. I put lego pieces inside to wedge it to not move.
The spinner was £38 with delivery from Ali Express. You can search "Baolian DA Spinner" on Ali Express to find it. It's really good quality spinner and works well with MAME.