Just ask for a sheet 6mm wider & taller than you want, and draw a 3mm rectangle around your actual design, centred within it...

That might work for really simple stuff, but at that point what's the point of using laser cutting with 0.01mm precision?

Well the engraving tolerance is actually placement tolerance and it's a little bit exaggerated. We have seen so complex parts that it's impossible to have it engraved perfectly. Normally, we overlay the actual product outline including the engraving design and it's aligned perfectly. For your application (control panels) sounds to be extremely easy to be perfect. You can drop us a line at hello@lasergist.com and discuss in detail.