I've just finished adding a programmable rev gauge to my carbon centre speedo. All the hard programming work was the handy work of Chippernut
I built v2.31 of Chippernut's project on a protoboard and decided to make the 7-segment display and rotary encoder removable.
Here are a few pictures of the build process.
I used a 1/4 Neopixel ring for the LEDs and used it's shape as a template to cut some dark acrylic to act as a diffuser and to provide a better overall look.
Masking tape was used to protect the glossy carbon and it made it easier to transfer the shape of the acrylic before cutting.