Source for engraved pistons in EU?

Hi,

Anyone have a recommended source for engraved pistons in the EU?

I have a bunch of push button switches that look to be very similar, but they have no markings on them. Is there any way I can use these? Number stickers covered with some sort of clear coat?

I bought a packet of 100 white plastic push buttons for a few Euros from a company in Hong Kong via Ebay. If I was doing my build again I'd look for a slightly higher quality or more robust - one is temperamental and another snapped off once whilst I was vigorously practising some Lizst. Annoyingly, from below the lowest keyboard so I had to take all four manuals out to repair it.

Useful tip - don't seal your console so well that you can't disassemble it in the event of urgent maintenance like a broken piston or non-sounding key.

Anyway, I laser printed piston numbers onto sheets of sticky backed acetate transparencies, cut tightly around them to minimise the area being stuck (originally I tried a large hole punch but its holes weren't clean enough to be reliable), then painted each piston with clear nail varnish. The ridge formed by the edge of the acetate on the piston is imperceptible and the black toner hasn't faded at all fifteen years later.