Laser engraved button

[Pietrogramma]

Hi Allanglenn, for first compliment for your great work and thanks for sharing it. I would construct the avionics of the Cessna C172, following your blog and your instruction.
I have a stupid request for you: can you explain how You have proceeded for engrave the buttons?
You printed they, then coloured black and finally you engraved with a laser, but how you found the exactly position where put the button printed and coloured?
You have realizated a jig for found the exact position or you have proceeded to sight,
Thanks and sorry for my bad english.