This isnt the first time this has been done on this forum, but maybe the first brava version, i mentioned this project on the stilo page where I got some useful info.
This is a desk clock made from a instrument cluster.
The hours is speed, & the mins is Rpm, fuel is how much of the day is left & seconds is temperature, time & date are shown as well as room temp.
On the back you can see the arduino in control, as well as a Spi to Can bus converter, and also a real time clock module with its battery backup.

After some fiddling I managed to get some pics to work, heres the front,
Divide speed by 10 to get the hours (100mph = 10 o clock), and multiply the rpm by 10 to get mins (3 krpm = 1/2 past):





And heres the back with the custom electronics mounted, the cable to the cluster is from the donor vehicle,
The board lineup is, arduino, spi to can converter and then the real time clock & battery, the stuff top left is a 5v regulator for the stuff on the board, as well as a temp sensor and a photocell that turns the backlights on when its dark.

If anyone's interested this can bus clock has been here on desk for the past 12 months continuously running the clock, and has been fine, not even any of the leds have faded.