You can build your own but there are some to buy. Take a look at TechMoan's channel on YouTube.
OK, weird question, if I have no guitar, but want a VU meter on my desk, can I just stick a cable in from say my Mac, no output, and have it do the VU dance all day long? Anyone wanted similar and found a better way to do this, with minimal homemade electronics skills?
As an alternative you could consider the Orange micro terror which you can now and then find for the £99 mark.
I’d love a good old mess/play around with one of these
nice very tempted (bin needing something with a headphone jack.....stupid roomates) :D