This entry is a compact art piece, crying out in appreciation of the venerable 555 timer. It's a persistence of vision display formed by 7 blue leds and 3 555 timers, which spells out 5 5 5 as it revolves.
Three 5's are created by tuning the first astable 555's period to complete 3 cycles in 1/4 of a revolution (the tachometer is high for 1/4 rev, low for 1/4, high for 1/4, low for 1/4, so you get two copies per full revolution).
The timings were worked out in an Excel spreadsheet (note: you might need to rename it back to xlsx to open it if it downloads as a ZIP).
Also check out my other entry, the Glitchovision 3000