[G6Tanuki]

A few decades back I built a 3-digit mains-voltage monitor; it used a "General Instrument Microelectronics" chip [the part-number started AY but I forget the rest of the number] and three of the rather-nice Monsanto MAN-series LED displays, the type that rather than being '7-segment' had lots of smaller LEDs so digits-with-curves could be rendered properly.

It cost around £100 in 1970s-money, and though the 3 digits were only about 1/3 inch high the electronics-box was about the size of a brick.

Today, LED mains-voltage monitors cost £2.50 shipped from China. Red, Green and Blue versions! These are also available at radio-rallies. I've recently acquired three, they'll be great as quick-and-dirty voltage monitors, avoiding tying-up a DVM unnecessarily. OK, they are only allegedly 1% accuracy - indeed the least-significant-digit counts up from zero in even-numbers only - but that still gives 1% accuracy at 250V and the ones I've got are close-enough to my DVM to be believable, whether running on the output of a 230-115V isolating transformer or connected direct to the mains.

No noticeable RFI from it between 1.6 and 30MHz, either!

The question comes - how to house one of these little displays in a 'case' that doesn't end up costing rather more than the display itself? I'm pondering a way to repurpose an offcut length of square black rainwater-downpipe and some old PCB material....