The Mojometer is far more sophisticated than the do-it-yourself projects on other sites.
Most of the meters documented on other sites are DIGITAL meters - not analogue. They're not easy to build unless you're very VERY handy with electronics overall.
This is a professional project - don't underestimate the gadget. Joe had the circuit board professionally made and assembled them all.
Then try pricing out the parts. Unless you buy in bulk, like we did, (or find a lucky surplus find) you'll pay about $15 for the meter itself plus $5 more for the superbright LEDs and components. Not mention wiring, solder, connectors, etc. Then you're going to have lots of fun tryin got adjust everything to get it to work right. Again - it's analogue and every one of these meters is slightly different.
Kermit