I do recall seeing visual metronomes but my searches come up blank, and I'm not sure that
they have MIDI inputs.
However, there are a couple of options that might
work.
First of all you could look at a MIDI to Light controller like
this. I'm not sure if it will do exactly
what you want, but the manufacturers might well be able to help.
Next up would
be a budget DMX lighting controller like this one from
Thomann. This has MIDI interfacing as well as lighting control. Again,
it is not clear whether or not it can follow a MIDI clock, but Thomann should be able to
tell you more.
And my third suggestion would be to go for a DIY solution.
This example looks
interesting and is designed to do exactly what you want. And I am certain you could
achieve something similar using an Arduino which might be easier for a beginner.
Hope that helps.
Andy
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When the going gets weird, the Weird turn Pro.